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1 | ================ |
2 | Event Histograms | |
3 | ================ | |
b8df4a36 | 4 | |
ea272257 | 5 | Documentation written by Tom Zanussi |
b8df4a36 TZ |
6 | |
7 | 1. Introduction | |
8 | =============== | |
9 | ||
10 | Histogram triggers are special event triggers that can be used to | |
11 | aggregate trace event data into histograms. For information on | |
5fb94e9c | 12 | trace events and event triggers, see Documentation/trace/events.rst. |
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13 | |
14 | ||
15 | 2. Histogram Trigger Command | |
16 | ============================ | |
17 | ||
18 | A histogram trigger command is an event trigger command that | |
19 | aggregates event hits into a hash table keyed on one or more trace | |
20 | event format fields (or stacktrace) and a set of running totals | |
21 | derived from one or more trace event format fields and/or event | |
22 | counts (hitcount). | |
23 | ||
ea272257 | 24 | The format of a hist trigger is as follows:: |
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25 | |
26 | hist:keys=<field1[,field2,...]>[:values=<field1[,field2,...]>] | |
27 | [:sort=<field1[,field2,...]>][:size=#entries][:pause][:continue] | |
5032b381 | 28 | [:clear][:name=histname1][:<handler>.<action>] [if <filter>] |
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29 | |
30 | When a matching event is hit, an entry is added to a hash table | |
31 | using the key(s) and value(s) named. Keys and values correspond to | |
32 | fields in the event's format description. Values must correspond to | |
33 | numeric fields - on an event hit, the value(s) will be added to a | |
34 | sum kept for that field. The special string 'hitcount' can be used | |
35 | in place of an explicit value field - this is simply a count of | |
36 | event hits. If 'values' isn't specified, an implicit 'hitcount' | |
37 | value will be automatically created and used as the only value. | |
38 | Keys can be any field, or the special string 'stacktrace', which | |
39 | will use the event's kernel stacktrace as the key. The keywords | |
40 | 'keys' or 'key' can be used to specify keys, and the keywords | |
41 | 'values', 'vals', or 'val' can be used to specify values. Compound | |
42 | keys consisting of up to two fields can be specified by the 'keys' | |
43 | keyword. Hashing a compound key produces a unique entry in the | |
44 | table for each unique combination of component keys, and can be | |
45 | useful for providing more fine-grained summaries of event data. | |
46 | Additionally, sort keys consisting of up to two fields can be | |
47 | specified by the 'sort' keyword. If more than one field is | |
48 | specified, the result will be a 'sort within a sort': the first key | |
49 | is taken to be the primary sort key and the second the secondary | |
50 | key. If a hist trigger is given a name using the 'name' parameter, | |
51 | its histogram data will be shared with other triggers of the same | |
52 | name, and trigger hits will update this common data. Only triggers | |
53 | with 'compatible' fields can be combined in this way; triggers are | |
54 | 'compatible' if the fields named in the trigger share the same | |
55 | number and type of fields and those fields also have the same names. | |
56 | Note that any two events always share the compatible 'hitcount' and | |
57 | 'stacktrace' fields and can therefore be combined using those | |
58 | fields, however pointless that may be. | |
59 | ||
60 | 'hist' triggers add a 'hist' file to each event's subdirectory. | |
61 | Reading the 'hist' file for the event will dump the hash table in | |
62 | its entirety to stdout. If there are multiple hist triggers | |
63 | attached to an event, there will be a table for each trigger in the | |
64 | output. The table displayed for a named trigger will be the same as | |
65 | any other instance having the same name. Each printed hash table | |
66 | entry is a simple list of the keys and values comprising the entry; | |
67 | keys are printed first and are delineated by curly braces, and are | |
68 | followed by the set of value fields for the entry. By default, | |
69 | numeric fields are displayed as base-10 integers. This can be | |
70 | modified by appending any of the following modifiers to the field | |
71 | name: | |
72 | ||
ea272257 | 73 | =========== ========================================== |
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74 | .hex display a number as a hex value |
75 | .sym display an address as a symbol | |
76 | .sym-offset display an address as a symbol and offset | |
77 | .syscall display a syscall id as a system call name | |
78 | .execname display a common_pid as a program name | |
442c9484 | 79 | .log2 display log2 value rather than raw number |
860f9f6b | 80 | .usecs display a common_timestamp in microseconds |
ea272257 | 81 | =========== ========================================== |
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82 | |
83 | Note that in general the semantics of a given field aren't | |
84 | interpreted when applying a modifier to it, but there are some | |
85 | restrictions to be aware of in this regard: | |
86 | ||
87 | - only the 'hex' modifier can be used for values (because values | |
88 | are essentially sums, and the other modifiers don't make sense | |
89 | in that context). | |
90 | - the 'execname' modifier can only be used on a 'common_pid'. The | |
91 | reason for this is that the execname is simply the 'comm' value | |
92 | saved for the 'current' process when an event was triggered, | |
93 | which is the same as the common_pid value saved by the event | |
94 | tracing code. Trying to apply that comm value to other pid | |
95 | values wouldn't be correct, and typically events that care save | |
96 | pid-specific comm fields in the event itself. | |
97 | ||
98 | A typical usage scenario would be the following to enable a hist | |
ea272257 | 99 | trigger, read its current contents, and then turn it off:: |
b8df4a36 | 100 | |
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101 | # echo 'hist:keys=skbaddr.hex:vals=len' > \ |
102 | /sys/kernel/debug/tracing/events/net/netif_rx/trigger | |
b8df4a36 | 103 | |
ea272257 | 104 | # cat /sys/kernel/debug/tracing/events/net/netif_rx/hist |
b8df4a36 | 105 | |
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106 | # echo '!hist:keys=skbaddr.hex:vals=len' > \ |
107 | /sys/kernel/debug/tracing/events/net/netif_rx/trigger | |
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108 | |
109 | The trigger file itself can be read to show the details of the | |
110 | currently attached hist trigger. This information is also displayed | |
111 | at the top of the 'hist' file when read. | |
112 | ||
113 | By default, the size of the hash table is 2048 entries. The 'size' | |
114 | parameter can be used to specify more or fewer than that. The units | |
115 | are in terms of hashtable entries - if a run uses more entries than | |
116 | specified, the results will show the number of 'drops', the number | |
117 | of hits that were ignored. The size should be a power of 2 between | |
118 | 128 and 131072 (any non- power-of-2 number specified will be rounded | |
119 | up). | |
120 | ||
121 | The 'sort' parameter can be used to specify a value field to sort | |
122 | on. The default if unspecified is 'hitcount' and the default sort | |
123 | order is 'ascending'. To sort in the opposite direction, append | |
124 | .descending' to the sort key. | |
125 | ||
126 | The 'pause' parameter can be used to pause an existing hist trigger | |
127 | or to start a hist trigger but not log any events until told to do | |
128 | so. 'continue' or 'cont' can be used to start or restart a paused | |
129 | hist trigger. | |
130 | ||
131 | The 'clear' parameter will clear the contents of a running hist | |
132 | trigger and leave its current paused/active state. | |
133 | ||
134 | Note that the 'pause', 'cont', and 'clear' parameters should be | |
135 | applied using 'append' shell operator ('>>') if applied to an | |
136 | existing trigger, rather than via the '>' operator, which will cause | |
137 | the trigger to be removed through truncation. | |
138 | ||
139 | - enable_hist/disable_hist | |
140 | ||
141 | The enable_hist and disable_hist triggers can be used to have one | |
142 | event conditionally start and stop another event's already-attached | |
143 | hist trigger. Any number of enable_hist and disable_hist triggers | |
144 | can be attached to a given event, allowing that event to kick off | |
145 | and stop aggregations on a host of other events. | |
146 | ||
ea272257 | 147 | The format is very similar to the enable/disable_event triggers:: |
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148 | |
149 | enable_hist:<system>:<event>[:count] | |
150 | disable_hist:<system>:<event>[:count] | |
151 | ||
152 | Instead of enabling or disabling the tracing of the target event | |
153 | into the trace buffer as the enable/disable_event triggers do, the | |
154 | enable/disable_hist triggers enable or disable the aggregation of | |
155 | the target event into a hash table. | |
156 | ||
157 | A typical usage scenario for the enable_hist/disable_hist triggers | |
158 | would be to first set up a paused hist trigger on some event, | |
159 | followed by an enable_hist/disable_hist pair that turns the hist | |
ea272257 | 160 | aggregation on and off when conditions of interest are hit:: |
b8df4a36 | 161 | |
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162 | # echo 'hist:keys=skbaddr.hex:vals=len:pause' > \ |
163 | /sys/kernel/debug/tracing/events/net/netif_receive_skb/trigger | |
b8df4a36 | 164 | |
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165 | # echo 'enable_hist:net:netif_receive_skb if filename==/usr/bin/wget' > \ |
166 | /sys/kernel/debug/tracing/events/sched/sched_process_exec/trigger | |
b8df4a36 | 167 | |
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168 | # echo 'disable_hist:net:netif_receive_skb if comm==wget' > \ |
169 | /sys/kernel/debug/tracing/events/sched/sched_process_exit/trigger | |
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170 | |
171 | The above sets up an initially paused hist trigger which is unpaused | |
172 | and starts aggregating events when a given program is executed, and | |
173 | which stops aggregating when the process exits and the hist trigger | |
174 | is paused again. | |
175 | ||
176 | The examples below provide a more concrete illustration of the | |
177 | concepts and typical usage patterns discussed above. | |
178 | ||
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179 | 'special' event fields |
180 | ------------------------ | |
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181 | |
182 | There are a number of 'special event fields' available for use as | |
183 | keys or values in a hist trigger. These look like and behave as if | |
184 | they were actual event fields, but aren't really part of the event's | |
185 | field definition or format file. They are however available for any | |
186 | event, and can be used anywhere an actual event field could be. | |
187 | They are: | |
188 | ||
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189 | ====================== ==== ======================================= |
190 | common_timestamp u64 timestamp (from ring buffer) associated | |
191 | with the event, in nanoseconds. May be | |
192 | modified by .usecs to have timestamps | |
193 | interpreted as microseconds. | |
194 | cpu int the cpu on which the event occurred. | |
195 | ====================== ==== ======================================= | |
b8df4a36 | 196 | |
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197 | Extended error information |
198 | -------------------------- | |
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199 | |
200 | For some error conditions encountered when invoking a hist trigger | |
201 | command, extended error information is available via the | |
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202 | tracing/error_log file. See Error Conditions in |
203 | :file:`Documentation/trace/ftrace.rst` for details. | |
f404da6e | 204 | |
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205 | 6.2 'hist' trigger examples |
206 | --------------------------- | |
207 | ||
208 | The first set of examples creates aggregations using the kmalloc | |
209 | event. The fields that can be used for the hist trigger are listed | |
ea272257 | 210 | in the kmalloc event's format file:: |
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211 | |
212 | # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/format | |
213 | name: kmalloc | |
214 | ID: 374 | |
215 | format: | |
216 | field:unsigned short common_type; offset:0; size:2; signed:0; | |
217 | field:unsigned char common_flags; offset:2; size:1; signed:0; | |
218 | field:unsigned char common_preempt_count; offset:3; size:1; signed:0; | |
219 | field:int common_pid; offset:4; size:4; signed:1; | |
220 | ||
221 | field:unsigned long call_site; offset:8; size:8; signed:0; | |
222 | field:const void * ptr; offset:16; size:8; signed:0; | |
223 | field:size_t bytes_req; offset:24; size:8; signed:0; | |
224 | field:size_t bytes_alloc; offset:32; size:8; signed:0; | |
225 | field:gfp_t gfp_flags; offset:40; size:4; signed:0; | |
226 | ||
227 | We'll start by creating a hist trigger that generates a simple table | |
228 | that lists the total number of bytes requested for each function in | |
ea272257 | 229 | the kernel that made one or more calls to kmalloc:: |
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230 | |
231 | # echo 'hist:key=call_site:val=bytes_req' > \ | |
232 | /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger | |
233 | ||
234 | This tells the tracing system to create a 'hist' trigger using the | |
235 | call_site field of the kmalloc event as the key for the table, which | |
236 | just means that each unique call_site address will have an entry | |
237 | created for it in the table. The 'val=bytes_req' parameter tells | |
238 | the hist trigger that for each unique entry (call_site) in the | |
239 | table, it should keep a running total of the number of bytes | |
240 | requested by that call_site. | |
241 | ||
242 | We'll let it run for awhile and then dump the contents of the 'hist' | |
243 | file in the kmalloc event's subdirectory (for readability, a number | |
ea272257 | 244 | of entries have been omitted):: |
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245 | |
246 | # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/hist | |
247 | # trigger info: hist:keys=call_site:vals=bytes_req:sort=hitcount:size=2048 [active] | |
248 | ||
249 | { call_site: 18446744072106379007 } hitcount: 1 bytes_req: 176 | |
250 | { call_site: 18446744071579557049 } hitcount: 1 bytes_req: 1024 | |
251 | { call_site: 18446744071580608289 } hitcount: 1 bytes_req: 16384 | |
252 | { call_site: 18446744071581827654 } hitcount: 1 bytes_req: 24 | |
253 | { call_site: 18446744071580700980 } hitcount: 1 bytes_req: 8 | |
254 | { call_site: 18446744071579359876 } hitcount: 1 bytes_req: 152 | |
255 | { call_site: 18446744071580795365 } hitcount: 3 bytes_req: 144 | |
256 | { call_site: 18446744071581303129 } hitcount: 3 bytes_req: 144 | |
257 | { call_site: 18446744071580713234 } hitcount: 4 bytes_req: 2560 | |
258 | { call_site: 18446744071580933750 } hitcount: 4 bytes_req: 736 | |
259 | . | |
260 | . | |
261 | . | |
262 | { call_site: 18446744072106047046 } hitcount: 69 bytes_req: 5576 | |
263 | { call_site: 18446744071582116407 } hitcount: 73 bytes_req: 2336 | |
264 | { call_site: 18446744072106054684 } hitcount: 136 bytes_req: 140504 | |
265 | { call_site: 18446744072106224230 } hitcount: 136 bytes_req: 19584 | |
266 | { call_site: 18446744072106078074 } hitcount: 153 bytes_req: 2448 | |
267 | { call_site: 18446744072106062406 } hitcount: 153 bytes_req: 36720 | |
268 | { call_site: 18446744071582507929 } hitcount: 153 bytes_req: 37088 | |
269 | { call_site: 18446744072102520590 } hitcount: 273 bytes_req: 10920 | |
270 | { call_site: 18446744071582143559 } hitcount: 358 bytes_req: 716 | |
271 | { call_site: 18446744072106465852 } hitcount: 417 bytes_req: 56712 | |
272 | { call_site: 18446744072102523378 } hitcount: 485 bytes_req: 27160 | |
273 | { call_site: 18446744072099568646 } hitcount: 1676 bytes_req: 33520 | |
274 | ||
275 | Totals: | |
276 | Hits: 4610 | |
277 | Entries: 45 | |
278 | Dropped: 0 | |
279 | ||
280 | The output displays a line for each entry, beginning with the key | |
281 | specified in the trigger, followed by the value(s) also specified in | |
282 | the trigger. At the beginning of the output is a line that displays | |
283 | the trigger info, which can also be displayed by reading the | |
ea272257 | 284 | 'trigger' file:: |
b8df4a36 TZ |
285 | |
286 | # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger | |
287 | hist:keys=call_site:vals=bytes_req:sort=hitcount:size=2048 [active] | |
288 | ||
289 | At the end of the output are a few lines that display the overall | |
290 | totals for the run. The 'Hits' field shows the total number of | |
291 | times the event trigger was hit, the 'Entries' field shows the total | |
292 | number of used entries in the hash table, and the 'Dropped' field | |
293 | shows the number of hits that were dropped because the number of | |
294 | used entries for the run exceeded the maximum number of entries | |
295 | allowed for the table (normally 0, but if not a hint that you may | |
296 | want to increase the size of the table using the 'size' parameter). | |
297 | ||
298 | Notice in the above output that there's an extra field, 'hitcount', | |
299 | which wasn't specified in the trigger. Also notice that in the | |
300 | trigger info output, there's a parameter, 'sort=hitcount', which | |
301 | wasn't specified in the trigger either. The reason for that is that | |
302 | every trigger implicitly keeps a count of the total number of hits | |
303 | attributed to a given entry, called the 'hitcount'. That hitcount | |
304 | information is explicitly displayed in the output, and in the | |
305 | absence of a user-specified sort parameter, is used as the default | |
306 | sort field. | |
307 | ||
308 | The value 'hitcount' can be used in place of an explicit value in | |
309 | the 'values' parameter if you don't really need to have any | |
310 | particular field summed and are mainly interested in hit | |
311 | frequencies. | |
312 | ||
313 | To turn the hist trigger off, simply call up the trigger in the | |
ea272257 | 314 | command history and re-execute it with a '!' prepended:: |
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315 | |
316 | # echo '!hist:key=call_site:val=bytes_req' > \ | |
317 | /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger | |
318 | ||
319 | Finally, notice that the call_site as displayed in the output above | |
320 | isn't really very useful. It's an address, but normally addresses | |
321 | are displayed in hex. To have a numeric field displayed as a hex | |
ea272257 | 322 | value, simply append '.hex' to the field name in the trigger:: |
b8df4a36 TZ |
323 | |
324 | # echo 'hist:key=call_site.hex:val=bytes_req' > \ | |
325 | /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger | |
326 | ||
327 | # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/hist | |
328 | # trigger info: hist:keys=call_site.hex:vals=bytes_req:sort=hitcount:size=2048 [active] | |
329 | ||
330 | { call_site: ffffffffa026b291 } hitcount: 1 bytes_req: 433 | |
331 | { call_site: ffffffffa07186ff } hitcount: 1 bytes_req: 176 | |
332 | { call_site: ffffffff811ae721 } hitcount: 1 bytes_req: 16384 | |
333 | { call_site: ffffffff811c5134 } hitcount: 1 bytes_req: 8 | |
334 | { call_site: ffffffffa04a9ebb } hitcount: 1 bytes_req: 511 | |
335 | { call_site: ffffffff8122e0a6 } hitcount: 1 bytes_req: 12 | |
336 | { call_site: ffffffff8107da84 } hitcount: 1 bytes_req: 152 | |
337 | { call_site: ffffffff812d8246 } hitcount: 1 bytes_req: 24 | |
338 | { call_site: ffffffff811dc1e5 } hitcount: 3 bytes_req: 144 | |
339 | { call_site: ffffffffa02515e8 } hitcount: 3 bytes_req: 648 | |
340 | { call_site: ffffffff81258159 } hitcount: 3 bytes_req: 144 | |
341 | { call_site: ffffffff811c80f4 } hitcount: 4 bytes_req: 544 | |
342 | . | |
343 | . | |
344 | . | |
345 | { call_site: ffffffffa06c7646 } hitcount: 106 bytes_req: 8024 | |
346 | { call_site: ffffffffa06cb246 } hitcount: 132 bytes_req: 31680 | |
347 | { call_site: ffffffffa06cef7a } hitcount: 132 bytes_req: 2112 | |
348 | { call_site: ffffffff8137e399 } hitcount: 132 bytes_req: 23232 | |
349 | { call_site: ffffffffa06c941c } hitcount: 185 bytes_req: 171360 | |
350 | { call_site: ffffffffa06f2a66 } hitcount: 185 bytes_req: 26640 | |
351 | { call_site: ffffffffa036a70e } hitcount: 265 bytes_req: 10600 | |
352 | { call_site: ffffffff81325447 } hitcount: 292 bytes_req: 584 | |
353 | { call_site: ffffffffa072da3c } hitcount: 446 bytes_req: 60656 | |
354 | { call_site: ffffffffa036b1f2 } hitcount: 526 bytes_req: 29456 | |
355 | { call_site: ffffffffa0099c06 } hitcount: 1780 bytes_req: 35600 | |
356 | ||
357 | Totals: | |
358 | Hits: 4775 | |
359 | Entries: 46 | |
360 | Dropped: 0 | |
361 | ||
362 | Even that's only marginally more useful - while hex values do look | |
363 | more like addresses, what users are typically more interested in | |
364 | when looking at text addresses are the corresponding symbols | |
365 | instead. To have an address displayed as symbolic value instead, | |
366 | simply append '.sym' or '.sym-offset' to the field name in the | |
ea272257 | 367 | trigger:: |
b8df4a36 TZ |
368 | |
369 | # echo 'hist:key=call_site.sym:val=bytes_req' > \ | |
370 | /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger | |
371 | ||
372 | # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/hist | |
373 | # trigger info: hist:keys=call_site.sym:vals=bytes_req:sort=hitcount:size=2048 [active] | |
374 | ||
375 | { call_site: [ffffffff810adcb9] syslog_print_all } hitcount: 1 bytes_req: 1024 | |
376 | { call_site: [ffffffff8154bc62] usb_control_msg } hitcount: 1 bytes_req: 8 | |
377 | { call_site: [ffffffffa00bf6fe] hidraw_send_report [hid] } hitcount: 1 bytes_req: 7 | |
378 | { call_site: [ffffffff8154acbe] usb_alloc_urb } hitcount: 1 bytes_req: 192 | |
379 | { call_site: [ffffffffa00bf1ca] hidraw_report_event [hid] } hitcount: 1 bytes_req: 7 | |
380 | { call_site: [ffffffff811e3a25] __seq_open_private } hitcount: 1 bytes_req: 40 | |
381 | { call_site: [ffffffff8109524a] alloc_fair_sched_group } hitcount: 2 bytes_req: 128 | |
382 | { call_site: [ffffffff811febd5] fsnotify_alloc_group } hitcount: 2 bytes_req: 528 | |
383 | { call_site: [ffffffff81440f58] __tty_buffer_request_room } hitcount: 2 bytes_req: 2624 | |
384 | { call_site: [ffffffff81200ba6] inotify_new_group } hitcount: 2 bytes_req: 96 | |
385 | { call_site: [ffffffffa05e19af] ieee80211_start_tx_ba_session [mac80211] } hitcount: 2 bytes_req: 464 | |
386 | { call_site: [ffffffff81672406] tcp_get_metrics } hitcount: 2 bytes_req: 304 | |
387 | { call_site: [ffffffff81097ec2] alloc_rt_sched_group } hitcount: 2 bytes_req: 128 | |
388 | { call_site: [ffffffff81089b05] sched_create_group } hitcount: 2 bytes_req: 1424 | |
389 | . | |
390 | . | |
391 | . | |
392 | { call_site: [ffffffffa04a580c] intel_crtc_page_flip [i915] } hitcount: 1185 bytes_req: 123240 | |
393 | { call_site: [ffffffffa0287592] drm_mode_page_flip_ioctl [drm] } hitcount: 1185 bytes_req: 104280 | |
394 | { call_site: [ffffffffa04c4a3c] intel_plane_duplicate_state [i915] } hitcount: 1402 bytes_req: 190672 | |
395 | { call_site: [ffffffff812891ca] ext4_find_extent } hitcount: 1518 bytes_req: 146208 | |
396 | { call_site: [ffffffffa029070e] drm_vma_node_allow [drm] } hitcount: 1746 bytes_req: 69840 | |
397 | { call_site: [ffffffffa045e7c4] i915_gem_do_execbuffer.isra.23 [i915] } hitcount: 2021 bytes_req: 792312 | |
398 | { call_site: [ffffffffa02911f2] drm_modeset_lock_crtc [drm] } hitcount: 2592 bytes_req: 145152 | |
399 | { call_site: [ffffffffa0489a66] intel_ring_begin [i915] } hitcount: 2629 bytes_req: 378576 | |
400 | { call_site: [ffffffffa046041c] i915_gem_execbuffer2 [i915] } hitcount: 2629 bytes_req: 3783248 | |
401 | { call_site: [ffffffff81325607] apparmor_file_alloc_security } hitcount: 5192 bytes_req: 10384 | |
402 | { call_site: [ffffffffa00b7c06] hid_report_raw_event [hid] } hitcount: 5529 bytes_req: 110584 | |
403 | { call_site: [ffffffff8131ebf7] aa_alloc_task_context } hitcount: 21943 bytes_req: 702176 | |
404 | { call_site: [ffffffff8125847d] ext4_htree_store_dirent } hitcount: 55759 bytes_req: 5074265 | |
405 | ||
406 | Totals: | |
407 | Hits: 109928 | |
408 | Entries: 71 | |
409 | Dropped: 0 | |
410 | ||
411 | Because the default sort key above is 'hitcount', the above shows a | |
412 | the list of call_sites by increasing hitcount, so that at the bottom | |
413 | we see the functions that made the most kmalloc calls during the | |
414 | run. If instead we we wanted to see the top kmalloc callers in | |
415 | terms of the number of bytes requested rather than the number of | |
416 | calls, and we wanted the top caller to appear at the top, we can use | |
ea272257 | 417 | the 'sort' parameter, along with the 'descending' modifier:: |
b8df4a36 TZ |
418 | |
419 | # echo 'hist:key=call_site.sym:val=bytes_req:sort=bytes_req.descending' > \ | |
420 | /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger | |
421 | ||
422 | # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/hist | |
423 | # trigger info: hist:keys=call_site.sym:vals=bytes_req:sort=bytes_req.descending:size=2048 [active] | |
424 | ||
425 | { call_site: [ffffffffa046041c] i915_gem_execbuffer2 [i915] } hitcount: 2186 bytes_req: 3397464 | |
426 | { call_site: [ffffffffa045e7c4] i915_gem_do_execbuffer.isra.23 [i915] } hitcount: 1790 bytes_req: 712176 | |
427 | { call_site: [ffffffff8125847d] ext4_htree_store_dirent } hitcount: 8132 bytes_req: 513135 | |
428 | { call_site: [ffffffff811e2a1b] seq_buf_alloc } hitcount: 106 bytes_req: 440128 | |
429 | { call_site: [ffffffffa0489a66] intel_ring_begin [i915] } hitcount: 2186 bytes_req: 314784 | |
430 | { call_site: [ffffffff812891ca] ext4_find_extent } hitcount: 2174 bytes_req: 208992 | |
431 | { call_site: [ffffffff811ae8e1] __kmalloc } hitcount: 8 bytes_req: 131072 | |
432 | { call_site: [ffffffffa04c4a3c] intel_plane_duplicate_state [i915] } hitcount: 859 bytes_req: 116824 | |
433 | { call_site: [ffffffffa02911f2] drm_modeset_lock_crtc [drm] } hitcount: 1834 bytes_req: 102704 | |
434 | { call_site: [ffffffffa04a580c] intel_crtc_page_flip [i915] } hitcount: 972 bytes_req: 101088 | |
435 | { call_site: [ffffffffa0287592] drm_mode_page_flip_ioctl [drm] } hitcount: 972 bytes_req: 85536 | |
436 | { call_site: [ffffffffa00b7c06] hid_report_raw_event [hid] } hitcount: 3333 bytes_req: 66664 | |
437 | { call_site: [ffffffff8137e559] sg_kmalloc } hitcount: 209 bytes_req: 61632 | |
438 | . | |
439 | . | |
440 | . | |
441 | { call_site: [ffffffff81095225] alloc_fair_sched_group } hitcount: 2 bytes_req: 128 | |
442 | { call_site: [ffffffff81097ec2] alloc_rt_sched_group } hitcount: 2 bytes_req: 128 | |
443 | { call_site: [ffffffff812d8406] copy_semundo } hitcount: 2 bytes_req: 48 | |
444 | { call_site: [ffffffff81200ba6] inotify_new_group } hitcount: 1 bytes_req: 48 | |
445 | { call_site: [ffffffffa027121a] drm_getmagic [drm] } hitcount: 1 bytes_req: 48 | |
446 | { call_site: [ffffffff811e3a25] __seq_open_private } hitcount: 1 bytes_req: 40 | |
447 | { call_site: [ffffffff811c52f4] bprm_change_interp } hitcount: 2 bytes_req: 16 | |
448 | { call_site: [ffffffff8154bc62] usb_control_msg } hitcount: 1 bytes_req: 8 | |
449 | { call_site: [ffffffffa00bf1ca] hidraw_report_event [hid] } hitcount: 1 bytes_req: 7 | |
450 | { call_site: [ffffffffa00bf6fe] hidraw_send_report [hid] } hitcount: 1 bytes_req: 7 | |
451 | ||
452 | Totals: | |
453 | Hits: 32133 | |
454 | Entries: 81 | |
455 | Dropped: 0 | |
456 | ||
457 | To display the offset and size information in addition to the symbol | |
ea272257 | 458 | name, just use 'sym-offset' instead:: |
b8df4a36 TZ |
459 | |
460 | # echo 'hist:key=call_site.sym-offset:val=bytes_req:sort=bytes_req.descending' > \ | |
461 | /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger | |
462 | ||
463 | # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/hist | |
464 | # trigger info: hist:keys=call_site.sym-offset:vals=bytes_req:sort=bytes_req.descending:size=2048 [active] | |
465 | ||
466 | { call_site: [ffffffffa046041c] i915_gem_execbuffer2+0x6c/0x2c0 [i915] } hitcount: 4569 bytes_req: 3163720 | |
467 | { call_site: [ffffffffa0489a66] intel_ring_begin+0xc6/0x1f0 [i915] } hitcount: 4569 bytes_req: 657936 | |
468 | { call_site: [ffffffffa045e7c4] i915_gem_do_execbuffer.isra.23+0x694/0x1020 [i915] } hitcount: 1519 bytes_req: 472936 | |
469 | { call_site: [ffffffffa045e646] i915_gem_do_execbuffer.isra.23+0x516/0x1020 [i915] } hitcount: 3050 bytes_req: 211832 | |
470 | { call_site: [ffffffff811e2a1b] seq_buf_alloc+0x1b/0x50 } hitcount: 34 bytes_req: 148384 | |
471 | { call_site: [ffffffffa04a580c] intel_crtc_page_flip+0xbc/0x870 [i915] } hitcount: 1385 bytes_req: 144040 | |
472 | { call_site: [ffffffff811ae8e1] __kmalloc+0x191/0x1b0 } hitcount: 8 bytes_req: 131072 | |
473 | { call_site: [ffffffffa0287592] drm_mode_page_flip_ioctl+0x282/0x360 [drm] } hitcount: 1385 bytes_req: 121880 | |
474 | { call_site: [ffffffffa02911f2] drm_modeset_lock_crtc+0x32/0x100 [drm] } hitcount: 1848 bytes_req: 103488 | |
475 | { call_site: [ffffffffa04c4a3c] intel_plane_duplicate_state+0x2c/0xa0 [i915] } hitcount: 461 bytes_req: 62696 | |
476 | { call_site: [ffffffffa029070e] drm_vma_node_allow+0x2e/0xd0 [drm] } hitcount: 1541 bytes_req: 61640 | |
477 | { call_site: [ffffffff815f8d7b] sk_prot_alloc+0xcb/0x1b0 } hitcount: 57 bytes_req: 57456 | |
478 | . | |
479 | . | |
480 | . | |
481 | { call_site: [ffffffff8109524a] alloc_fair_sched_group+0x5a/0x1a0 } hitcount: 2 bytes_req: 128 | |
482 | { call_site: [ffffffffa027b921] drm_vm_open_locked+0x31/0xa0 [drm] } hitcount: 3 bytes_req: 96 | |
483 | { call_site: [ffffffff8122e266] proc_self_follow_link+0x76/0xb0 } hitcount: 8 bytes_req: 96 | |
484 | { call_site: [ffffffff81213e80] load_elf_binary+0x240/0x1650 } hitcount: 3 bytes_req: 84 | |
485 | { call_site: [ffffffff8154bc62] usb_control_msg+0x42/0x110 } hitcount: 1 bytes_req: 8 | |
486 | { call_site: [ffffffffa00bf6fe] hidraw_send_report+0x7e/0x1a0 [hid] } hitcount: 1 bytes_req: 7 | |
487 | { call_site: [ffffffffa00bf1ca] hidraw_report_event+0x8a/0x120 [hid] } hitcount: 1 bytes_req: 7 | |
488 | ||
489 | Totals: | |
490 | Hits: 26098 | |
491 | Entries: 64 | |
492 | Dropped: 0 | |
493 | ||
494 | We can also add multiple fields to the 'values' parameter. For | |
495 | example, we might want to see the total number of bytes allocated | |
496 | alongside bytes requested, and display the result sorted by bytes | |
ea272257 | 497 | allocated in a descending order:: |
b8df4a36 TZ |
498 | |
499 | # echo 'hist:keys=call_site.sym:values=bytes_req,bytes_alloc:sort=bytes_alloc.descending' > \ | |
500 | /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger | |
501 | ||
502 | # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/hist | |
503 | # trigger info: hist:keys=call_site.sym:vals=bytes_req,bytes_alloc:sort=bytes_alloc.descending:size=2048 [active] | |
504 | ||
505 | { call_site: [ffffffffa046041c] i915_gem_execbuffer2 [i915] } hitcount: 7403 bytes_req: 4084360 bytes_alloc: 5958016 | |
506 | { call_site: [ffffffff811e2a1b] seq_buf_alloc } hitcount: 541 bytes_req: 2213968 bytes_alloc: 2228224 | |
507 | { call_site: [ffffffffa0489a66] intel_ring_begin [i915] } hitcount: 7404 bytes_req: 1066176 bytes_alloc: 1421568 | |
508 | { call_site: [ffffffffa045e7c4] i915_gem_do_execbuffer.isra.23 [i915] } hitcount: 1565 bytes_req: 557368 bytes_alloc: 1037760 | |
509 | { call_site: [ffffffff8125847d] ext4_htree_store_dirent } hitcount: 9557 bytes_req: 595778 bytes_alloc: 695744 | |
510 | { call_site: [ffffffffa045e646] i915_gem_do_execbuffer.isra.23 [i915] } hitcount: 5839 bytes_req: 430680 bytes_alloc: 470400 | |
511 | { call_site: [ffffffffa04c4a3c] intel_plane_duplicate_state [i915] } hitcount: 2388 bytes_req: 324768 bytes_alloc: 458496 | |
512 | { call_site: [ffffffffa02911f2] drm_modeset_lock_crtc [drm] } hitcount: 3911 bytes_req: 219016 bytes_alloc: 250304 | |
513 | { call_site: [ffffffff815f8d7b] sk_prot_alloc } hitcount: 235 bytes_req: 236880 bytes_alloc: 240640 | |
514 | { call_site: [ffffffff8137e559] sg_kmalloc } hitcount: 557 bytes_req: 169024 bytes_alloc: 221760 | |
515 | { call_site: [ffffffffa00b7c06] hid_report_raw_event [hid] } hitcount: 9378 bytes_req: 187548 bytes_alloc: 206312 | |
516 | { call_site: [ffffffffa04a580c] intel_crtc_page_flip [i915] } hitcount: 1519 bytes_req: 157976 bytes_alloc: 194432 | |
517 | . | |
518 | . | |
519 | . | |
520 | { call_site: [ffffffff8109bd3b] sched_autogroup_create_attach } hitcount: 2 bytes_req: 144 bytes_alloc: 192 | |
521 | { call_site: [ffffffff81097ee8] alloc_rt_sched_group } hitcount: 2 bytes_req: 128 bytes_alloc: 128 | |
522 | { call_site: [ffffffff8109524a] alloc_fair_sched_group } hitcount: 2 bytes_req: 128 bytes_alloc: 128 | |
523 | { call_site: [ffffffff81095225] alloc_fair_sched_group } hitcount: 2 bytes_req: 128 bytes_alloc: 128 | |
524 | { call_site: [ffffffff81097ec2] alloc_rt_sched_group } hitcount: 2 bytes_req: 128 bytes_alloc: 128 | |
525 | { call_site: [ffffffff81213e80] load_elf_binary } hitcount: 3 bytes_req: 84 bytes_alloc: 96 | |
526 | { call_site: [ffffffff81079a2e] kthread_create_on_node } hitcount: 1 bytes_req: 56 bytes_alloc: 64 | |
527 | { call_site: [ffffffffa00bf6fe] hidraw_send_report [hid] } hitcount: 1 bytes_req: 7 bytes_alloc: 8 | |
528 | { call_site: [ffffffff8154bc62] usb_control_msg } hitcount: 1 bytes_req: 8 bytes_alloc: 8 | |
529 | { call_site: [ffffffffa00bf1ca] hidraw_report_event [hid] } hitcount: 1 bytes_req: 7 bytes_alloc: 8 | |
530 | ||
531 | Totals: | |
532 | Hits: 66598 | |
533 | Entries: 65 | |
534 | Dropped: 0 | |
535 | ||
536 | Finally, to finish off our kmalloc example, instead of simply having | |
537 | the hist trigger display symbolic call_sites, we can have the hist | |
538 | trigger additionally display the complete set of kernel stack traces | |
539 | that led to each call_site. To do that, we simply use the special | |
ea272257 | 540 | value 'stacktrace' for the key parameter:: |
b8df4a36 TZ |
541 | |
542 | # echo 'hist:keys=stacktrace:values=bytes_req,bytes_alloc:sort=bytes_alloc' > \ | |
543 | /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger | |
544 | ||
545 | The above trigger will use the kernel stack trace in effect when an | |
546 | event is triggered as the key for the hash table. This allows the | |
547 | enumeration of every kernel callpath that led up to a particular | |
548 | event, along with a running total of any of the event fields for | |
549 | that event. Here we tally bytes requested and bytes allocated for | |
550 | every callpath in the system that led up to a kmalloc (in this case | |
ea272257 | 551 | every callpath to a kmalloc for a kernel compile):: |
b8df4a36 TZ |
552 | |
553 | # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/hist | |
554 | # trigger info: hist:keys=stacktrace:vals=bytes_req,bytes_alloc:sort=bytes_alloc:size=2048 [active] | |
555 | ||
556 | { stacktrace: | |
557 | __kmalloc_track_caller+0x10b/0x1a0 | |
558 | kmemdup+0x20/0x50 | |
559 | hidraw_report_event+0x8a/0x120 [hid] | |
560 | hid_report_raw_event+0x3ea/0x440 [hid] | |
561 | hid_input_report+0x112/0x190 [hid] | |
562 | hid_irq_in+0xc2/0x260 [usbhid] | |
563 | __usb_hcd_giveback_urb+0x72/0x120 | |
564 | usb_giveback_urb_bh+0x9e/0xe0 | |
565 | tasklet_hi_action+0xf8/0x100 | |
566 | __do_softirq+0x114/0x2c0 | |
567 | irq_exit+0xa5/0xb0 | |
568 | do_IRQ+0x5a/0xf0 | |
569 | ret_from_intr+0x0/0x30 | |
570 | cpuidle_enter+0x17/0x20 | |
571 | cpu_startup_entry+0x315/0x3e0 | |
572 | rest_init+0x7c/0x80 | |
573 | } hitcount: 3 bytes_req: 21 bytes_alloc: 24 | |
574 | { stacktrace: | |
575 | __kmalloc_track_caller+0x10b/0x1a0 | |
576 | kmemdup+0x20/0x50 | |
577 | hidraw_report_event+0x8a/0x120 [hid] | |
578 | hid_report_raw_event+0x3ea/0x440 [hid] | |
579 | hid_input_report+0x112/0x190 [hid] | |
580 | hid_irq_in+0xc2/0x260 [usbhid] | |
581 | __usb_hcd_giveback_urb+0x72/0x120 | |
582 | usb_giveback_urb_bh+0x9e/0xe0 | |
583 | tasklet_hi_action+0xf8/0x100 | |
584 | __do_softirq+0x114/0x2c0 | |
585 | irq_exit+0xa5/0xb0 | |
586 | do_IRQ+0x5a/0xf0 | |
587 | ret_from_intr+0x0/0x30 | |
588 | } hitcount: 3 bytes_req: 21 bytes_alloc: 24 | |
589 | { stacktrace: | |
590 | kmem_cache_alloc_trace+0xeb/0x150 | |
591 | aa_alloc_task_context+0x27/0x40 | |
592 | apparmor_cred_prepare+0x1f/0x50 | |
593 | security_prepare_creds+0x16/0x20 | |
594 | prepare_creds+0xdf/0x1a0 | |
595 | SyS_capset+0xb5/0x200 | |
596 | system_call_fastpath+0x12/0x6a | |
597 | } hitcount: 1 bytes_req: 32 bytes_alloc: 32 | |
598 | . | |
599 | . | |
600 | . | |
601 | { stacktrace: | |
602 | __kmalloc+0x11b/0x1b0 | |
603 | i915_gem_execbuffer2+0x6c/0x2c0 [i915] | |
604 | drm_ioctl+0x349/0x670 [drm] | |
605 | do_vfs_ioctl+0x2f0/0x4f0 | |
606 | SyS_ioctl+0x81/0xa0 | |
607 | system_call_fastpath+0x12/0x6a | |
608 | } hitcount: 17726 bytes_req: 13944120 bytes_alloc: 19593808 | |
609 | { stacktrace: | |
610 | __kmalloc+0x11b/0x1b0 | |
611 | load_elf_phdrs+0x76/0xa0 | |
612 | load_elf_binary+0x102/0x1650 | |
613 | search_binary_handler+0x97/0x1d0 | |
614 | do_execveat_common.isra.34+0x551/0x6e0 | |
615 | SyS_execve+0x3a/0x50 | |
616 | return_from_execve+0x0/0x23 | |
617 | } hitcount: 33348 bytes_req: 17152128 bytes_alloc: 20226048 | |
618 | { stacktrace: | |
619 | kmem_cache_alloc_trace+0xeb/0x150 | |
620 | apparmor_file_alloc_security+0x27/0x40 | |
621 | security_file_alloc+0x16/0x20 | |
622 | get_empty_filp+0x93/0x1c0 | |
623 | path_openat+0x31/0x5f0 | |
624 | do_filp_open+0x3a/0x90 | |
625 | do_sys_open+0x128/0x220 | |
626 | SyS_open+0x1e/0x20 | |
627 | system_call_fastpath+0x12/0x6a | |
628 | } hitcount: 4766422 bytes_req: 9532844 bytes_alloc: 38131376 | |
629 | { stacktrace: | |
630 | __kmalloc+0x11b/0x1b0 | |
631 | seq_buf_alloc+0x1b/0x50 | |
632 | seq_read+0x2cc/0x370 | |
633 | proc_reg_read+0x3d/0x80 | |
634 | __vfs_read+0x28/0xe0 | |
635 | vfs_read+0x86/0x140 | |
636 | SyS_read+0x46/0xb0 | |
637 | system_call_fastpath+0x12/0x6a | |
638 | } hitcount: 19133 bytes_req: 78368768 bytes_alloc: 78368768 | |
639 | ||
640 | Totals: | |
641 | Hits: 6085872 | |
642 | Entries: 253 | |
643 | Dropped: 0 | |
644 | ||
645 | If you key a hist trigger on common_pid, in order for example to | |
646 | gather and display sorted totals for each process, you can use the | |
647 | special .execname modifier to display the executable names for the | |
648 | processes in the table rather than raw pids. The example below | |
ea272257 | 649 | keeps a per-process sum of total bytes read:: |
b8df4a36 TZ |
650 | |
651 | # echo 'hist:key=common_pid.execname:val=count:sort=count.descending' > \ | |
652 | /sys/kernel/debug/tracing/events/syscalls/sys_enter_read/trigger | |
653 | ||
654 | # cat /sys/kernel/debug/tracing/events/syscalls/sys_enter_read/hist | |
655 | # trigger info: hist:keys=common_pid.execname:vals=count:sort=count.descending:size=2048 [active] | |
656 | ||
657 | { common_pid: gnome-terminal [ 3196] } hitcount: 280 count: 1093512 | |
658 | { common_pid: Xorg [ 1309] } hitcount: 525 count: 256640 | |
659 | { common_pid: compiz [ 2889] } hitcount: 59 count: 254400 | |
660 | { common_pid: bash [ 8710] } hitcount: 3 count: 66369 | |
661 | { common_pid: dbus-daemon-lau [ 8703] } hitcount: 49 count: 47739 | |
662 | { common_pid: irqbalance [ 1252] } hitcount: 27 count: 27648 | |
663 | { common_pid: 01ifupdown [ 8705] } hitcount: 3 count: 17216 | |
664 | { common_pid: dbus-daemon [ 772] } hitcount: 10 count: 12396 | |
665 | { common_pid: Socket Thread [ 8342] } hitcount: 11 count: 11264 | |
666 | { common_pid: nm-dhcp-client. [ 8701] } hitcount: 6 count: 7424 | |
667 | { common_pid: gmain [ 1315] } hitcount: 18 count: 6336 | |
668 | . | |
669 | . | |
670 | . | |
671 | { common_pid: postgres [ 1892] } hitcount: 2 count: 32 | |
672 | { common_pid: postgres [ 1891] } hitcount: 2 count: 32 | |
673 | { common_pid: gmain [ 8704] } hitcount: 2 count: 32 | |
674 | { common_pid: upstart-dbus-br [ 2740] } hitcount: 21 count: 21 | |
675 | { common_pid: nm-dispatcher.a [ 8696] } hitcount: 1 count: 16 | |
676 | { common_pid: indicator-datet [ 2904] } hitcount: 1 count: 16 | |
677 | { common_pid: gdbus [ 2998] } hitcount: 1 count: 16 | |
678 | { common_pid: rtkit-daemon [ 2052] } hitcount: 1 count: 8 | |
679 | { common_pid: init [ 1] } hitcount: 2 count: 2 | |
680 | ||
681 | Totals: | |
682 | Hits: 2116 | |
683 | Entries: 51 | |
684 | Dropped: 0 | |
685 | ||
686 | Similarly, if you key a hist trigger on syscall id, for example to | |
687 | gather and display a list of systemwide syscall hits, you can use | |
688 | the special .syscall modifier to display the syscall names rather | |
689 | than raw ids. The example below keeps a running total of syscall | |
ea272257 | 690 | counts for the system during the run:: |
b8df4a36 TZ |
691 | |
692 | # echo 'hist:key=id.syscall:val=hitcount' > \ | |
693 | /sys/kernel/debug/tracing/events/raw_syscalls/sys_enter/trigger | |
694 | ||
695 | # cat /sys/kernel/debug/tracing/events/raw_syscalls/sys_enter/hist | |
696 | # trigger info: hist:keys=id.syscall:vals=hitcount:sort=hitcount:size=2048 [active] | |
697 | ||
698 | { id: sys_fsync [ 74] } hitcount: 1 | |
699 | { id: sys_newuname [ 63] } hitcount: 1 | |
700 | { id: sys_prctl [157] } hitcount: 1 | |
701 | { id: sys_statfs [137] } hitcount: 1 | |
702 | { id: sys_symlink [ 88] } hitcount: 1 | |
703 | { id: sys_sendmmsg [307] } hitcount: 1 | |
704 | { id: sys_semctl [ 66] } hitcount: 1 | |
705 | { id: sys_readlink [ 89] } hitcount: 3 | |
706 | { id: sys_bind [ 49] } hitcount: 3 | |
707 | { id: sys_getsockname [ 51] } hitcount: 3 | |
708 | { id: sys_unlink [ 87] } hitcount: 3 | |
709 | { id: sys_rename [ 82] } hitcount: 4 | |
710 | { id: unknown_syscall [ 58] } hitcount: 4 | |
711 | { id: sys_connect [ 42] } hitcount: 4 | |
712 | { id: sys_getpid [ 39] } hitcount: 4 | |
713 | . | |
714 | . | |
715 | . | |
716 | { id: sys_rt_sigprocmask [ 14] } hitcount: 952 | |
717 | { id: sys_futex [202] } hitcount: 1534 | |
718 | { id: sys_write [ 1] } hitcount: 2689 | |
719 | { id: sys_setitimer [ 38] } hitcount: 2797 | |
720 | { id: sys_read [ 0] } hitcount: 3202 | |
721 | { id: sys_select [ 23] } hitcount: 3773 | |
722 | { id: sys_writev [ 20] } hitcount: 4531 | |
723 | { id: sys_poll [ 7] } hitcount: 8314 | |
724 | { id: sys_recvmsg [ 47] } hitcount: 13738 | |
725 | { id: sys_ioctl [ 16] } hitcount: 21843 | |
726 | ||
727 | Totals: | |
728 | Hits: 67612 | |
729 | Entries: 72 | |
730 | Dropped: 0 | |
731 | ||
ea272257 MCC |
732 | The syscall counts above provide a rough overall picture of system |
733 | call activity on the system; we can see for example that the most | |
734 | popular system call on this system was the 'sys_ioctl' system call. | |
b8df4a36 | 735 | |
ea272257 MCC |
736 | We can use 'compound' keys to refine that number and provide some |
737 | further insight as to which processes exactly contribute to the | |
738 | overall ioctl count. | |
b8df4a36 | 739 | |
ea272257 MCC |
740 | The command below keeps a hitcount for every unique combination of |
741 | system call id and pid - the end result is essentially a table | |
742 | that keeps a per-pid sum of system call hits. The results are | |
743 | sorted using the system call id as the primary key, and the | |
744 | hitcount sum as the secondary key:: | |
b8df4a36 TZ |
745 | |
746 | # echo 'hist:key=id.syscall,common_pid.execname:val=hitcount:sort=id,hitcount' > \ | |
747 | /sys/kernel/debug/tracing/events/raw_syscalls/sys_enter/trigger | |
748 | ||
749 | # cat /sys/kernel/debug/tracing/events/raw_syscalls/sys_enter/hist | |
750 | # trigger info: hist:keys=id.syscall,common_pid.execname:vals=hitcount:sort=id.syscall,hitcount:size=2048 [active] | |
751 | ||
752 | { id: sys_read [ 0], common_pid: rtkit-daemon [ 1877] } hitcount: 1 | |
753 | { id: sys_read [ 0], common_pid: gdbus [ 2976] } hitcount: 1 | |
754 | { id: sys_read [ 0], common_pid: console-kit-dae [ 3400] } hitcount: 1 | |
755 | { id: sys_read [ 0], common_pid: postgres [ 1865] } hitcount: 1 | |
756 | { id: sys_read [ 0], common_pid: deja-dup-monito [ 3543] } hitcount: 2 | |
757 | { id: sys_read [ 0], common_pid: NetworkManager [ 890] } hitcount: 2 | |
758 | { id: sys_read [ 0], common_pid: evolution-calen [ 3048] } hitcount: 2 | |
759 | { id: sys_read [ 0], common_pid: postgres [ 1864] } hitcount: 2 | |
760 | { id: sys_read [ 0], common_pid: nm-applet [ 3022] } hitcount: 2 | |
761 | { id: sys_read [ 0], common_pid: whoopsie [ 1212] } hitcount: 2 | |
762 | . | |
763 | . | |
764 | . | |
765 | { id: sys_ioctl [ 16], common_pid: bash [ 8479] } hitcount: 1 | |
766 | { id: sys_ioctl [ 16], common_pid: bash [ 3472] } hitcount: 12 | |
767 | { id: sys_ioctl [ 16], common_pid: gnome-terminal [ 3199] } hitcount: 16 | |
768 | { id: sys_ioctl [ 16], common_pid: Xorg [ 1267] } hitcount: 1808 | |
769 | { id: sys_ioctl [ 16], common_pid: compiz [ 2994] } hitcount: 5580 | |
770 | . | |
771 | . | |
772 | . | |
773 | { id: sys_waitid [247], common_pid: upstart-dbus-br [ 2690] } hitcount: 3 | |
774 | { id: sys_waitid [247], common_pid: upstart-dbus-br [ 2688] } hitcount: 16 | |
775 | { id: sys_inotify_add_watch [254], common_pid: gmain [ 975] } hitcount: 2 | |
776 | { id: sys_inotify_add_watch [254], common_pid: gmain [ 3204] } hitcount: 4 | |
777 | { id: sys_inotify_add_watch [254], common_pid: gmain [ 2888] } hitcount: 4 | |
778 | { id: sys_inotify_add_watch [254], common_pid: gmain [ 3003] } hitcount: 4 | |
779 | { id: sys_inotify_add_watch [254], common_pid: gmain [ 2873] } hitcount: 4 | |
780 | { id: sys_inotify_add_watch [254], common_pid: gmain [ 3196] } hitcount: 6 | |
781 | { id: sys_openat [257], common_pid: java [ 2623] } hitcount: 2 | |
782 | { id: sys_eventfd2 [290], common_pid: ibus-ui-gtk3 [ 2760] } hitcount: 4 | |
783 | { id: sys_eventfd2 [290], common_pid: compiz [ 2994] } hitcount: 6 | |
784 | ||
785 | Totals: | |
786 | Hits: 31536 | |
787 | Entries: 323 | |
788 | Dropped: 0 | |
789 | ||
ea272257 MCC |
790 | The above list does give us a breakdown of the ioctl syscall by |
791 | pid, but it also gives us quite a bit more than that, which we | |
792 | don't really care about at the moment. Since we know the syscall | |
793 | id for sys_ioctl (16, displayed next to the sys_ioctl name), we | |
794 | can use that to filter out all the other syscalls:: | |
b8df4a36 TZ |
795 | |
796 | # echo 'hist:key=id.syscall,common_pid.execname:val=hitcount:sort=id,hitcount if id == 16' > \ | |
797 | /sys/kernel/debug/tracing/events/raw_syscalls/sys_enter/trigger | |
798 | ||
799 | # cat /sys/kernel/debug/tracing/events/raw_syscalls/sys_enter/hist | |
800 | # trigger info: hist:keys=id.syscall,common_pid.execname:vals=hitcount:sort=id.syscall,hitcount:size=2048 if id == 16 [active] | |
801 | ||
802 | { id: sys_ioctl [ 16], common_pid: gmain [ 2769] } hitcount: 1 | |
803 | { id: sys_ioctl [ 16], common_pid: evolution-addre [ 8571] } hitcount: 1 | |
804 | { id: sys_ioctl [ 16], common_pid: gmain [ 3003] } hitcount: 1 | |
805 | { id: sys_ioctl [ 16], common_pid: gmain [ 2781] } hitcount: 1 | |
806 | { id: sys_ioctl [ 16], common_pid: gmain [ 2829] } hitcount: 1 | |
807 | { id: sys_ioctl [ 16], common_pid: bash [ 8726] } hitcount: 1 | |
808 | { id: sys_ioctl [ 16], common_pid: bash [ 8508] } hitcount: 1 | |
809 | { id: sys_ioctl [ 16], common_pid: gmain [ 2970] } hitcount: 1 | |
810 | { id: sys_ioctl [ 16], common_pid: gmain [ 2768] } hitcount: 1 | |
811 | . | |
812 | . | |
813 | . | |
814 | { id: sys_ioctl [ 16], common_pid: pool [ 8559] } hitcount: 45 | |
815 | { id: sys_ioctl [ 16], common_pid: pool [ 8555] } hitcount: 48 | |
816 | { id: sys_ioctl [ 16], common_pid: pool [ 8551] } hitcount: 48 | |
817 | { id: sys_ioctl [ 16], common_pid: avahi-daemon [ 896] } hitcount: 66 | |
818 | { id: sys_ioctl [ 16], common_pid: Xorg [ 1267] } hitcount: 26674 | |
819 | { id: sys_ioctl [ 16], common_pid: compiz [ 2994] } hitcount: 73443 | |
820 | ||
821 | Totals: | |
822 | Hits: 101162 | |
823 | Entries: 103 | |
824 | Dropped: 0 | |
825 | ||
ea272257 MCC |
826 | The above output shows that 'compiz' and 'Xorg' are far and away |
827 | the heaviest ioctl callers (which might lead to questions about | |
828 | whether they really need to be making all those calls and to | |
829 | possible avenues for further investigation.) | |
b8df4a36 | 830 | |
ea272257 MCC |
831 | The compound key examples used a key and a sum value (hitcount) to |
832 | sort the output, but we can just as easily use two keys instead. | |
833 | Here's an example where we use a compound key composed of the the | |
834 | common_pid and size event fields. Sorting with pid as the primary | |
835 | key and 'size' as the secondary key allows us to display an | |
836 | ordered summary of the recvfrom sizes, with counts, received by | |
837 | each process:: | |
b8df4a36 TZ |
838 | |
839 | # echo 'hist:key=common_pid.execname,size:val=hitcount:sort=common_pid,size' > \ | |
840 | /sys/kernel/debug/tracing/events/syscalls/sys_enter_recvfrom/trigger | |
841 | ||
842 | # cat /sys/kernel/debug/tracing/events/syscalls/sys_enter_recvfrom/hist | |
843 | # trigger info: hist:keys=common_pid.execname,size:vals=hitcount:sort=common_pid.execname,size:size=2048 [active] | |
844 | ||
845 | { common_pid: smbd [ 784], size: 4 } hitcount: 1 | |
846 | { common_pid: dnsmasq [ 1412], size: 4096 } hitcount: 672 | |
847 | { common_pid: postgres [ 1796], size: 1000 } hitcount: 6 | |
848 | { common_pid: postgres [ 1867], size: 1000 } hitcount: 10 | |
849 | { common_pid: bamfdaemon [ 2787], size: 28 } hitcount: 2 | |
850 | { common_pid: bamfdaemon [ 2787], size: 14360 } hitcount: 1 | |
851 | { common_pid: compiz [ 2994], size: 8 } hitcount: 1 | |
852 | { common_pid: compiz [ 2994], size: 20 } hitcount: 11 | |
853 | { common_pid: gnome-terminal [ 3199], size: 4 } hitcount: 2 | |
854 | { common_pid: firefox [ 8817], size: 4 } hitcount: 1 | |
855 | { common_pid: firefox [ 8817], size: 8 } hitcount: 5 | |
856 | { common_pid: firefox [ 8817], size: 588 } hitcount: 2 | |
857 | { common_pid: firefox [ 8817], size: 628 } hitcount: 1 | |
858 | { common_pid: firefox [ 8817], size: 6944 } hitcount: 1 | |
859 | { common_pid: firefox [ 8817], size: 408880 } hitcount: 2 | |
860 | { common_pid: firefox [ 8822], size: 8 } hitcount: 2 | |
861 | { common_pid: firefox [ 8822], size: 160 } hitcount: 2 | |
862 | { common_pid: firefox [ 8822], size: 320 } hitcount: 2 | |
863 | { common_pid: firefox [ 8822], size: 352 } hitcount: 1 | |
864 | . | |
865 | . | |
866 | . | |
867 | { common_pid: pool [ 8923], size: 1960 } hitcount: 10 | |
868 | { common_pid: pool [ 8923], size: 2048 } hitcount: 10 | |
869 | { common_pid: pool [ 8924], size: 1960 } hitcount: 10 | |
870 | { common_pid: pool [ 8924], size: 2048 } hitcount: 10 | |
871 | { common_pid: pool [ 8928], size: 1964 } hitcount: 4 | |
872 | { common_pid: pool [ 8928], size: 1965 } hitcount: 2 | |
873 | { common_pid: pool [ 8928], size: 2048 } hitcount: 6 | |
874 | { common_pid: pool [ 8929], size: 1982 } hitcount: 1 | |
875 | { common_pid: pool [ 8929], size: 2048 } hitcount: 1 | |
876 | ||
877 | Totals: | |
878 | Hits: 2016 | |
879 | Entries: 224 | |
880 | Dropped: 0 | |
881 | ||
882 | The above example also illustrates the fact that although a compound | |
883 | key is treated as a single entity for hashing purposes, the sub-keys | |
884 | it's composed of can be accessed independently. | |
885 | ||
886 | The next example uses a string field as the hash key and | |
887 | demonstrates how you can manually pause and continue a hist trigger. | |
888 | In this example, we'll aggregate fork counts and don't expect a | |
889 | large number of entries in the hash table, so we'll drop it to a | |
ea272257 | 890 | much smaller number, say 256:: |
b8df4a36 TZ |
891 | |
892 | # echo 'hist:key=child_comm:val=hitcount:size=256' > \ | |
893 | /sys/kernel/debug/tracing/events/sched/sched_process_fork/trigger | |
894 | ||
895 | # cat /sys/kernel/debug/tracing/events/sched/sched_process_fork/hist | |
896 | # trigger info: hist:keys=child_comm:vals=hitcount:sort=hitcount:size=256 [active] | |
897 | ||
898 | { child_comm: dconf worker } hitcount: 1 | |
899 | { child_comm: ibus-daemon } hitcount: 1 | |
900 | { child_comm: whoopsie } hitcount: 1 | |
901 | { child_comm: smbd } hitcount: 1 | |
902 | { child_comm: gdbus } hitcount: 1 | |
903 | { child_comm: kthreadd } hitcount: 1 | |
904 | { child_comm: dconf worker } hitcount: 1 | |
905 | { child_comm: evolution-alarm } hitcount: 2 | |
906 | { child_comm: Socket Thread } hitcount: 2 | |
907 | { child_comm: postgres } hitcount: 2 | |
908 | { child_comm: bash } hitcount: 3 | |
909 | { child_comm: compiz } hitcount: 3 | |
910 | { child_comm: evolution-sourc } hitcount: 4 | |
911 | { child_comm: dhclient } hitcount: 4 | |
912 | { child_comm: pool } hitcount: 5 | |
913 | { child_comm: nm-dispatcher.a } hitcount: 8 | |
914 | { child_comm: firefox } hitcount: 8 | |
915 | { child_comm: dbus-daemon } hitcount: 8 | |
916 | { child_comm: glib-pacrunner } hitcount: 10 | |
917 | { child_comm: evolution } hitcount: 23 | |
918 | ||
919 | Totals: | |
920 | Hits: 89 | |
921 | Entries: 20 | |
922 | Dropped: 0 | |
923 | ||
924 | If we want to pause the hist trigger, we can simply append :pause to | |
925 | the command that started the trigger. Notice that the trigger info | |
ea272257 | 926 | displays as [paused]:: |
b8df4a36 TZ |
927 | |
928 | # echo 'hist:key=child_comm:val=hitcount:size=256:pause' >> \ | |
929 | /sys/kernel/debug/tracing/events/sched/sched_process_fork/trigger | |
930 | ||
931 | # cat /sys/kernel/debug/tracing/events/sched/sched_process_fork/hist | |
932 | # trigger info: hist:keys=child_comm:vals=hitcount:sort=hitcount:size=256 [paused] | |
933 | ||
934 | { child_comm: dconf worker } hitcount: 1 | |
935 | { child_comm: kthreadd } hitcount: 1 | |
936 | { child_comm: dconf worker } hitcount: 1 | |
937 | { child_comm: gdbus } hitcount: 1 | |
938 | { child_comm: ibus-daemon } hitcount: 1 | |
939 | { child_comm: Socket Thread } hitcount: 2 | |
940 | { child_comm: evolution-alarm } hitcount: 2 | |
941 | { child_comm: smbd } hitcount: 2 | |
942 | { child_comm: bash } hitcount: 3 | |
943 | { child_comm: whoopsie } hitcount: 3 | |
944 | { child_comm: compiz } hitcount: 3 | |
945 | { child_comm: evolution-sourc } hitcount: 4 | |
946 | { child_comm: pool } hitcount: 5 | |
947 | { child_comm: postgres } hitcount: 6 | |
948 | { child_comm: firefox } hitcount: 8 | |
949 | { child_comm: dhclient } hitcount: 10 | |
950 | { child_comm: emacs } hitcount: 12 | |
951 | { child_comm: dbus-daemon } hitcount: 20 | |
952 | { child_comm: nm-dispatcher.a } hitcount: 20 | |
953 | { child_comm: evolution } hitcount: 35 | |
954 | { child_comm: glib-pacrunner } hitcount: 59 | |
955 | ||
956 | Totals: | |
957 | Hits: 199 | |
958 | Entries: 21 | |
959 | Dropped: 0 | |
960 | ||
961 | To manually continue having the trigger aggregate events, append | |
962 | :cont instead. Notice that the trigger info displays as [active] | |
ea272257 | 963 | again, and the data has changed:: |
b8df4a36 TZ |
964 | |
965 | # echo 'hist:key=child_comm:val=hitcount:size=256:cont' >> \ | |
966 | /sys/kernel/debug/tracing/events/sched/sched_process_fork/trigger | |
967 | ||
968 | # cat /sys/kernel/debug/tracing/events/sched/sched_process_fork/hist | |
969 | # trigger info: hist:keys=child_comm:vals=hitcount:sort=hitcount:size=256 [active] | |
970 | ||
971 | { child_comm: dconf worker } hitcount: 1 | |
972 | { child_comm: dconf worker } hitcount: 1 | |
973 | { child_comm: kthreadd } hitcount: 1 | |
974 | { child_comm: gdbus } hitcount: 1 | |
975 | { child_comm: ibus-daemon } hitcount: 1 | |
976 | { child_comm: Socket Thread } hitcount: 2 | |
977 | { child_comm: evolution-alarm } hitcount: 2 | |
978 | { child_comm: smbd } hitcount: 2 | |
979 | { child_comm: whoopsie } hitcount: 3 | |
980 | { child_comm: compiz } hitcount: 3 | |
981 | { child_comm: evolution-sourc } hitcount: 4 | |
982 | { child_comm: bash } hitcount: 5 | |
983 | { child_comm: pool } hitcount: 5 | |
984 | { child_comm: postgres } hitcount: 6 | |
985 | { child_comm: firefox } hitcount: 8 | |
986 | { child_comm: dhclient } hitcount: 11 | |
987 | { child_comm: emacs } hitcount: 12 | |
988 | { child_comm: dbus-daemon } hitcount: 22 | |
989 | { child_comm: nm-dispatcher.a } hitcount: 22 | |
990 | { child_comm: evolution } hitcount: 35 | |
991 | { child_comm: glib-pacrunner } hitcount: 59 | |
992 | ||
993 | Totals: | |
994 | Hits: 206 | |
995 | Entries: 21 | |
996 | Dropped: 0 | |
997 | ||
998 | The previous example showed how to start and stop a hist trigger by | |
999 | appending 'pause' and 'continue' to the hist trigger command. A | |
1000 | hist trigger can also be started in a paused state by initially | |
1001 | starting the trigger with ':pause' appended. This allows you to | |
1002 | start the trigger only when you're ready to start collecting data | |
1003 | and not before. For example, you could start the trigger in a | |
1004 | paused state, then unpause it and do something you want to measure, | |
1005 | then pause the trigger again when done. | |
1006 | ||
1007 | Of course, doing this manually can be difficult and error-prone, but | |
1008 | it is possible to automatically start and stop a hist trigger based | |
1009 | on some condition, via the enable_hist and disable_hist triggers. | |
1010 | ||
1011 | For example, suppose we wanted to take a look at the relative | |
1012 | weights in terms of skb length for each callpath that leads to a | |
fe4ec72c | 1013 | netif_receive_skb event when downloading a decent-sized file using |
b8df4a36 TZ |
1014 | wget. |
1015 | ||
1016 | First we set up an initially paused stacktrace trigger on the | |
ea272257 | 1017 | netif_receive_skb event:: |
b8df4a36 TZ |
1018 | |
1019 | # echo 'hist:key=stacktrace:vals=len:pause' > \ | |
1020 | /sys/kernel/debug/tracing/events/net/netif_receive_skb/trigger | |
1021 | ||
1022 | Next, we set up an 'enable_hist' trigger on the sched_process_exec | |
1023 | event, with an 'if filename==/usr/bin/wget' filter. The effect of | |
1024 | this new trigger is that it will 'unpause' the hist trigger we just | |
1025 | set up on netif_receive_skb if and only if it sees a | |
1026 | sched_process_exec event with a filename of '/usr/bin/wget'. When | |
1027 | that happens, all netif_receive_skb events are aggregated into a | |
ea272257 | 1028 | hash table keyed on stacktrace:: |
b8df4a36 TZ |
1029 | |
1030 | # echo 'enable_hist:net:netif_receive_skb if filename==/usr/bin/wget' > \ | |
1031 | /sys/kernel/debug/tracing/events/sched/sched_process_exec/trigger | |
1032 | ||
1033 | The aggregation continues until the netif_receive_skb is paused | |
1034 | again, which is what the following disable_hist event does by | |
1035 | creating a similar setup on the sched_process_exit event, using the | |
ea272257 | 1036 | filter 'comm==wget':: |
b8df4a36 TZ |
1037 | |
1038 | # echo 'disable_hist:net:netif_receive_skb if comm==wget' > \ | |
1039 | /sys/kernel/debug/tracing/events/sched/sched_process_exit/trigger | |
1040 | ||
1041 | Whenever a process exits and the comm field of the disable_hist | |
1042 | trigger filter matches 'comm==wget', the netif_receive_skb hist | |
1043 | trigger is disabled. | |
1044 | ||
1045 | The overall effect is that netif_receive_skb events are aggregated | |
1046 | into the hash table for only the duration of the wget. Executing a | |
1047 | wget command and then listing the 'hist' file will display the | |
ea272257 | 1048 | output generated by the wget command:: |
b8df4a36 TZ |
1049 | |
1050 | $ wget https://www.kernel.org/pub/linux/kernel/v3.x/patch-3.19.xz | |
1051 | ||
1052 | # cat /sys/kernel/debug/tracing/events/net/netif_receive_skb/hist | |
1053 | # trigger info: hist:keys=stacktrace:vals=len:sort=hitcount:size=2048 [paused] | |
1054 | ||
1055 | { stacktrace: | |
1056 | __netif_receive_skb_core+0x46d/0x990 | |
1057 | __netif_receive_skb+0x18/0x60 | |
1058 | netif_receive_skb_internal+0x23/0x90 | |
1059 | napi_gro_receive+0xc8/0x100 | |
1060 | ieee80211_deliver_skb+0xd6/0x270 [mac80211] | |
1061 | ieee80211_rx_handlers+0xccf/0x22f0 [mac80211] | |
1062 | ieee80211_prepare_and_rx_handle+0x4e7/0xc40 [mac80211] | |
1063 | ieee80211_rx+0x31d/0x900 [mac80211] | |
1064 | iwlagn_rx_reply_rx+0x3db/0x6f0 [iwldvm] | |
1065 | iwl_rx_dispatch+0x8e/0xf0 [iwldvm] | |
1066 | iwl_pcie_irq_handler+0xe3c/0x12f0 [iwlwifi] | |
1067 | irq_thread_fn+0x20/0x50 | |
1068 | irq_thread+0x11f/0x150 | |
1069 | kthread+0xd2/0xf0 | |
1070 | ret_from_fork+0x42/0x70 | |
1071 | } hitcount: 85 len: 28884 | |
1072 | { stacktrace: | |
1073 | __netif_receive_skb_core+0x46d/0x990 | |
1074 | __netif_receive_skb+0x18/0x60 | |
1075 | netif_receive_skb_internal+0x23/0x90 | |
1076 | napi_gro_complete+0xa4/0xe0 | |
1077 | dev_gro_receive+0x23a/0x360 | |
1078 | napi_gro_receive+0x30/0x100 | |
1079 | ieee80211_deliver_skb+0xd6/0x270 [mac80211] | |
1080 | ieee80211_rx_handlers+0xccf/0x22f0 [mac80211] | |
1081 | ieee80211_prepare_and_rx_handle+0x4e7/0xc40 [mac80211] | |
1082 | ieee80211_rx+0x31d/0x900 [mac80211] | |
1083 | iwlagn_rx_reply_rx+0x3db/0x6f0 [iwldvm] | |
1084 | iwl_rx_dispatch+0x8e/0xf0 [iwldvm] | |
1085 | iwl_pcie_irq_handler+0xe3c/0x12f0 [iwlwifi] | |
1086 | irq_thread_fn+0x20/0x50 | |
1087 | irq_thread+0x11f/0x150 | |
1088 | kthread+0xd2/0xf0 | |
1089 | } hitcount: 98 len: 664329 | |
1090 | { stacktrace: | |
1091 | __netif_receive_skb_core+0x46d/0x990 | |
1092 | __netif_receive_skb+0x18/0x60 | |
1093 | process_backlog+0xa8/0x150 | |
1094 | net_rx_action+0x15d/0x340 | |
1095 | __do_softirq+0x114/0x2c0 | |
1096 | do_softirq_own_stack+0x1c/0x30 | |
1097 | do_softirq+0x65/0x70 | |
1098 | __local_bh_enable_ip+0xb5/0xc0 | |
1099 | ip_finish_output+0x1f4/0x840 | |
1100 | ip_output+0x6b/0xc0 | |
1101 | ip_local_out_sk+0x31/0x40 | |
1102 | ip_send_skb+0x1a/0x50 | |
1103 | udp_send_skb+0x173/0x2a0 | |
1104 | udp_sendmsg+0x2bf/0x9f0 | |
1105 | inet_sendmsg+0x64/0xa0 | |
1106 | sock_sendmsg+0x3d/0x50 | |
1107 | } hitcount: 115 len: 13030 | |
1108 | { stacktrace: | |
1109 | __netif_receive_skb_core+0x46d/0x990 | |
1110 | __netif_receive_skb+0x18/0x60 | |
1111 | netif_receive_skb_internal+0x23/0x90 | |
1112 | napi_gro_complete+0xa4/0xe0 | |
1113 | napi_gro_flush+0x6d/0x90 | |
1114 | iwl_pcie_irq_handler+0x92a/0x12f0 [iwlwifi] | |
1115 | irq_thread_fn+0x20/0x50 | |
1116 | irq_thread+0x11f/0x150 | |
1117 | kthread+0xd2/0xf0 | |
1118 | ret_from_fork+0x42/0x70 | |
1119 | } hitcount: 934 len: 5512212 | |
1120 | ||
1121 | Totals: | |
1122 | Hits: 1232 | |
1123 | Entries: 4 | |
1124 | Dropped: 0 | |
1125 | ||
1126 | The above shows all the netif_receive_skb callpaths and their total | |
1127 | lengths for the duration of the wget command. | |
1128 | ||
1129 | The 'clear' hist trigger param can be used to clear the hash table. | |
1130 | Suppose we wanted to try another run of the previous example but | |
1131 | this time also wanted to see the complete list of events that went | |
1132 | into the histogram. In order to avoid having to set everything up | |
ea272257 | 1133 | again, we can just clear the histogram first:: |
b8df4a36 TZ |
1134 | |
1135 | # echo 'hist:key=stacktrace:vals=len:clear' >> \ | |
1136 | /sys/kernel/debug/tracing/events/net/netif_receive_skb/trigger | |
1137 | ||
1138 | Just to verify that it is in fact cleared, here's what we now see in | |
ea272257 | 1139 | the hist file:: |
b8df4a36 TZ |
1140 | |
1141 | # cat /sys/kernel/debug/tracing/events/net/netif_receive_skb/hist | |
1142 | # trigger info: hist:keys=stacktrace:vals=len:sort=hitcount:size=2048 [paused] | |
1143 | ||
1144 | Totals: | |
1145 | Hits: 0 | |
1146 | Entries: 0 | |
1147 | Dropped: 0 | |
1148 | ||
1149 | Since we want to see the detailed list of every netif_receive_skb | |
1150 | event occurring during the new run, which are in fact the same | |
1151 | events being aggregated into the hash table, we add some additional | |
1152 | 'enable_event' events to the triggering sched_process_exec and | |
ea272257 | 1153 | sched_process_exit events as such:: |
b8df4a36 TZ |
1154 | |
1155 | # echo 'enable_event:net:netif_receive_skb if filename==/usr/bin/wget' > \ | |
1156 | /sys/kernel/debug/tracing/events/sched/sched_process_exec/trigger | |
1157 | ||
1158 | # echo 'disable_event:net:netif_receive_skb if comm==wget' > \ | |
1159 | /sys/kernel/debug/tracing/events/sched/sched_process_exit/trigger | |
1160 | ||
1161 | If you read the trigger files for the sched_process_exec and | |
1162 | sched_process_exit triggers, you should see two triggers for each: | |
1163 | one enabling/disabling the hist aggregation and the other | |
ea272257 | 1164 | enabling/disabling the logging of events:: |
b8df4a36 TZ |
1165 | |
1166 | # cat /sys/kernel/debug/tracing/events/sched/sched_process_exec/trigger | |
1167 | enable_event:net:netif_receive_skb:unlimited if filename==/usr/bin/wget | |
1168 | enable_hist:net:netif_receive_skb:unlimited if filename==/usr/bin/wget | |
1169 | ||
1170 | # cat /sys/kernel/debug/tracing/events/sched/sched_process_exit/trigger | |
1171 | enable_event:net:netif_receive_skb:unlimited if comm==wget | |
1172 | disable_hist:net:netif_receive_skb:unlimited if comm==wget | |
1173 | ||
1174 | In other words, whenever either of the sched_process_exec or | |
1175 | sched_process_exit events is hit and matches 'wget', it enables or | |
1176 | disables both the histogram and the event log, and what you end up | |
1177 | with is a hash table and set of events just covering the specified | |
ea272257 | 1178 | duration. Run the wget command again:: |
b8df4a36 TZ |
1179 | |
1180 | $ wget https://www.kernel.org/pub/linux/kernel/v3.x/patch-3.19.xz | |
1181 | ||
1182 | Displaying the 'hist' file should show something similar to what you | |
1183 | saw in the last run, but this time you should also see the | |
ea272257 | 1184 | individual events in the trace file:: |
b8df4a36 TZ |
1185 | |
1186 | # cat /sys/kernel/debug/tracing/trace | |
1187 | ||
1188 | # tracer: nop | |
1189 | # | |
1190 | # entries-in-buffer/entries-written: 183/1426 #P:4 | |
1191 | # | |
1192 | # _-----=> irqs-off | |
1193 | # / _----=> need-resched | |
1194 | # | / _---=> hardirq/softirq | |
1195 | # || / _--=> preempt-depth | |
1196 | # ||| / delay | |
1197 | # TASK-PID CPU# |||| TIMESTAMP FUNCTION | |
1198 | # | | | |||| | | | |
1199 | wget-15108 [000] ..s1 31769.606929: netif_receive_skb: dev=lo skbaddr=ffff88009c353100 len=60 | |
1200 | wget-15108 [000] ..s1 31769.606999: netif_receive_skb: dev=lo skbaddr=ffff88009c353200 len=60 | |
1201 | dnsmasq-1382 [000] ..s1 31769.677652: netif_receive_skb: dev=lo skbaddr=ffff88009c352b00 len=130 | |
1202 | dnsmasq-1382 [000] ..s1 31769.685917: netif_receive_skb: dev=lo skbaddr=ffff88009c352200 len=138 | |
1203 | ##### CPU 2 buffer started #### | |
1204 | irq/29-iwlwifi-559 [002] ..s. 31772.031529: netif_receive_skb: dev=wlan0 skbaddr=ffff88009d433d00 len=2948 | |
1205 | irq/29-iwlwifi-559 [002] ..s. 31772.031572: netif_receive_skb: dev=wlan0 skbaddr=ffff88009d432200 len=1500 | |
1206 | irq/29-iwlwifi-559 [002] ..s. 31772.032196: netif_receive_skb: dev=wlan0 skbaddr=ffff88009d433100 len=2948 | |
1207 | irq/29-iwlwifi-559 [002] ..s. 31772.032761: netif_receive_skb: dev=wlan0 skbaddr=ffff88009d433000 len=2948 | |
1208 | irq/29-iwlwifi-559 [002] ..s. 31772.033220: netif_receive_skb: dev=wlan0 skbaddr=ffff88009d432e00 len=1500 | |
1209 | . | |
1210 | . | |
1211 | . | |
1212 | ||
1213 | The following example demonstrates how multiple hist triggers can be | |
1214 | attached to a given event. This capability can be useful for | |
1215 | creating a set of different summaries derived from the same set of | |
1216 | events, or for comparing the effects of different filters, among | |
ea272257 | 1217 | other things:: |
b8df4a36 TZ |
1218 | |
1219 | # echo 'hist:keys=skbaddr.hex:vals=len if len < 0' >> \ | |
1220 | /sys/kernel/debug/tracing/events/net/netif_receive_skb/trigger | |
1221 | # echo 'hist:keys=skbaddr.hex:vals=len if len > 4096' >> \ | |
1222 | /sys/kernel/debug/tracing/events/net/netif_receive_skb/trigger | |
1223 | # echo 'hist:keys=skbaddr.hex:vals=len if len == 256' >> \ | |
1224 | /sys/kernel/debug/tracing/events/net/netif_receive_skb/trigger | |
1225 | # echo 'hist:keys=skbaddr.hex:vals=len' >> \ | |
1226 | /sys/kernel/debug/tracing/events/net/netif_receive_skb/trigger | |
1227 | # echo 'hist:keys=len:vals=common_preempt_count' >> \ | |
1228 | /sys/kernel/debug/tracing/events/net/netif_receive_skb/trigger | |
1229 | ||
1230 | The above set of commands create four triggers differing only in | |
1231 | their filters, along with a completely different though fairly | |
1232 | nonsensical trigger. Note that in order to append multiple hist | |
1233 | triggers to the same file, you should use the '>>' operator to | |
1234 | append them ('>' will also add the new hist trigger, but will remove | |
1235 | any existing hist triggers beforehand). | |
1236 | ||
1237 | Displaying the contents of the 'hist' file for the event shows the | |
ea272257 | 1238 | contents of all five histograms:: |
b8df4a36 TZ |
1239 | |
1240 | # cat /sys/kernel/debug/tracing/events/net/netif_receive_skb/hist | |
1241 | ||
1242 | # event histogram | |
1243 | # | |
1244 | # trigger info: hist:keys=len:vals=hitcount,common_preempt_count:sort=hitcount:size=2048 [active] | |
1245 | # | |
1246 | ||
1247 | { len: 176 } hitcount: 1 common_preempt_count: 0 | |
1248 | { len: 223 } hitcount: 1 common_preempt_count: 0 | |
1249 | { len: 4854 } hitcount: 1 common_preempt_count: 0 | |
1250 | { len: 395 } hitcount: 1 common_preempt_count: 0 | |
1251 | { len: 177 } hitcount: 1 common_preempt_count: 0 | |
1252 | { len: 446 } hitcount: 1 common_preempt_count: 0 | |
1253 | { len: 1601 } hitcount: 1 common_preempt_count: 0 | |
1254 | . | |
1255 | . | |
1256 | . | |
1257 | { len: 1280 } hitcount: 66 common_preempt_count: 0 | |
1258 | { len: 116 } hitcount: 81 common_preempt_count: 40 | |
1259 | { len: 708 } hitcount: 112 common_preempt_count: 0 | |
1260 | { len: 46 } hitcount: 221 common_preempt_count: 0 | |
1261 | { len: 1264 } hitcount: 458 common_preempt_count: 0 | |
1262 | ||
1263 | Totals: | |
1264 | Hits: 1428 | |
1265 | Entries: 147 | |
1266 | Dropped: 0 | |
1267 | ||
1268 | ||
1269 | # event histogram | |
1270 | # | |
1271 | # trigger info: hist:keys=skbaddr.hex:vals=hitcount,len:sort=hitcount:size=2048 [active] | |
1272 | # | |
1273 | ||
1274 | { skbaddr: ffff8800baee5e00 } hitcount: 1 len: 130 | |
1275 | { skbaddr: ffff88005f3d5600 } hitcount: 1 len: 1280 | |
1276 | { skbaddr: ffff88005f3d4900 } hitcount: 1 len: 1280 | |
1277 | { skbaddr: ffff88009fed6300 } hitcount: 1 len: 115 | |
1278 | { skbaddr: ffff88009fe0ad00 } hitcount: 1 len: 115 | |
1279 | { skbaddr: ffff88008cdb1900 } hitcount: 1 len: 46 | |
1280 | { skbaddr: ffff880064b5ef00 } hitcount: 1 len: 118 | |
1281 | { skbaddr: ffff880044e3c700 } hitcount: 1 len: 60 | |
1282 | { skbaddr: ffff880100065900 } hitcount: 1 len: 46 | |
1283 | { skbaddr: ffff8800d46bd500 } hitcount: 1 len: 116 | |
1284 | { skbaddr: ffff88005f3d5f00 } hitcount: 1 len: 1280 | |
1285 | { skbaddr: ffff880100064700 } hitcount: 1 len: 365 | |
1286 | { skbaddr: ffff8800badb6f00 } hitcount: 1 len: 60 | |
1287 | . | |
1288 | . | |
1289 | . | |
1290 | { skbaddr: ffff88009fe0be00 } hitcount: 27 len: 24677 | |
1291 | { skbaddr: ffff88009fe0a400 } hitcount: 27 len: 23052 | |
1292 | { skbaddr: ffff88009fe0b700 } hitcount: 31 len: 25589 | |
1293 | { skbaddr: ffff88009fe0b600 } hitcount: 32 len: 27326 | |
1294 | { skbaddr: ffff88006a462800 } hitcount: 68 len: 71678 | |
1295 | { skbaddr: ffff88006a463700 } hitcount: 70 len: 72678 | |
1296 | { skbaddr: ffff88006a462b00 } hitcount: 71 len: 77589 | |
1297 | { skbaddr: ffff88006a463600 } hitcount: 73 len: 71307 | |
1298 | { skbaddr: ffff88006a462200 } hitcount: 81 len: 81032 | |
1299 | ||
1300 | Totals: | |
1301 | Hits: 1451 | |
1302 | Entries: 318 | |
1303 | Dropped: 0 | |
1304 | ||
1305 | ||
1306 | # event histogram | |
1307 | # | |
1308 | # trigger info: hist:keys=skbaddr.hex:vals=hitcount,len:sort=hitcount:size=2048 if len == 256 [active] | |
1309 | # | |
1310 | ||
1311 | ||
1312 | Totals: | |
1313 | Hits: 0 | |
1314 | Entries: 0 | |
1315 | Dropped: 0 | |
1316 | ||
1317 | ||
1318 | # event histogram | |
1319 | # | |
1320 | # trigger info: hist:keys=skbaddr.hex:vals=hitcount,len:sort=hitcount:size=2048 if len > 4096 [active] | |
1321 | # | |
1322 | ||
1323 | { skbaddr: ffff88009fd2c300 } hitcount: 1 len: 7212 | |
1324 | { skbaddr: ffff8800d2bcce00 } hitcount: 1 len: 7212 | |
1325 | { skbaddr: ffff8800d2bcd700 } hitcount: 1 len: 7212 | |
1326 | { skbaddr: ffff8800d2bcda00 } hitcount: 1 len: 21492 | |
1327 | { skbaddr: ffff8800ae2e2d00 } hitcount: 1 len: 7212 | |
1328 | { skbaddr: ffff8800d2bcdb00 } hitcount: 1 len: 7212 | |
1329 | { skbaddr: ffff88006a4df500 } hitcount: 1 len: 4854 | |
1330 | { skbaddr: ffff88008ce47b00 } hitcount: 1 len: 18636 | |
1331 | { skbaddr: ffff8800ae2e2200 } hitcount: 1 len: 12924 | |
1332 | { skbaddr: ffff88005f3e1000 } hitcount: 1 len: 4356 | |
1333 | { skbaddr: ffff8800d2bcdc00 } hitcount: 2 len: 24420 | |
1334 | { skbaddr: ffff8800d2bcc200 } hitcount: 2 len: 12996 | |
1335 | ||
1336 | Totals: | |
1337 | Hits: 14 | |
1338 | Entries: 12 | |
1339 | Dropped: 0 | |
1340 | ||
1341 | ||
1342 | # event histogram | |
1343 | # | |
1344 | # trigger info: hist:keys=skbaddr.hex:vals=hitcount,len:sort=hitcount:size=2048 if len < 0 [active] | |
1345 | # | |
1346 | ||
1347 | ||
1348 | Totals: | |
1349 | Hits: 0 | |
1350 | Entries: 0 | |
1351 | Dropped: 0 | |
1352 | ||
1353 | Named triggers can be used to have triggers share a common set of | |
1354 | histogram data. This capability is mostly useful for combining the | |
1355 | output of events generated by tracepoints contained inside inline | |
1356 | functions, but names can be used in a hist trigger on any event. | |
1357 | For example, these two triggers when hit will update the same 'len' | |
ea272257 | 1358 | field in the shared 'foo' histogram data:: |
b8df4a36 TZ |
1359 | |
1360 | # echo 'hist:name=foo:keys=skbaddr.hex:vals=len' > \ | |
1361 | /sys/kernel/debug/tracing/events/net/netif_receive_skb/trigger | |
1362 | # echo 'hist:name=foo:keys=skbaddr.hex:vals=len' > \ | |
1363 | /sys/kernel/debug/tracing/events/net/netif_rx/trigger | |
1364 | ||
1365 | You can see that they're updating common histogram data by reading | |
ea272257 | 1366 | each event's hist files at the same time:: |
b8df4a36 TZ |
1367 | |
1368 | # cat /sys/kernel/debug/tracing/events/net/netif_receive_skb/hist; | |
1369 | cat /sys/kernel/debug/tracing/events/net/netif_rx/hist | |
1370 | ||
1371 | # event histogram | |
1372 | # | |
1373 | # trigger info: hist:name=foo:keys=skbaddr.hex:vals=hitcount,len:sort=hitcount:size=2048 [active] | |
1374 | # | |
1375 | ||
1376 | { skbaddr: ffff88000ad53500 } hitcount: 1 len: 46 | |
1377 | { skbaddr: ffff8800af5a1500 } hitcount: 1 len: 76 | |
1378 | { skbaddr: ffff8800d62a1900 } hitcount: 1 len: 46 | |
1379 | { skbaddr: ffff8800d2bccb00 } hitcount: 1 len: 468 | |
1380 | { skbaddr: ffff8800d3c69900 } hitcount: 1 len: 46 | |
1381 | { skbaddr: ffff88009ff09100 } hitcount: 1 len: 52 | |
1382 | { skbaddr: ffff88010f13ab00 } hitcount: 1 len: 168 | |
1383 | { skbaddr: ffff88006a54f400 } hitcount: 1 len: 46 | |
1384 | { skbaddr: ffff8800d2bcc500 } hitcount: 1 len: 260 | |
1385 | { skbaddr: ffff880064505000 } hitcount: 1 len: 46 | |
1386 | { skbaddr: ffff8800baf24e00 } hitcount: 1 len: 32 | |
1387 | { skbaddr: ffff88009fe0ad00 } hitcount: 1 len: 46 | |
1388 | { skbaddr: ffff8800d3edff00 } hitcount: 1 len: 44 | |
1389 | { skbaddr: ffff88009fe0b400 } hitcount: 1 len: 168 | |
1390 | { skbaddr: ffff8800a1c55a00 } hitcount: 1 len: 40 | |
1391 | { skbaddr: ffff8800d2bcd100 } hitcount: 1 len: 40 | |
1392 | { skbaddr: ffff880064505f00 } hitcount: 1 len: 174 | |
1393 | { skbaddr: ffff8800a8bff200 } hitcount: 1 len: 160 | |
1394 | { skbaddr: ffff880044e3cc00 } hitcount: 1 len: 76 | |
1395 | { skbaddr: ffff8800a8bfe700 } hitcount: 1 len: 46 | |
1396 | { skbaddr: ffff8800d2bcdc00 } hitcount: 1 len: 32 | |
1397 | { skbaddr: ffff8800a1f64800 } hitcount: 1 len: 46 | |
1398 | { skbaddr: ffff8800d2bcde00 } hitcount: 1 len: 988 | |
1399 | { skbaddr: ffff88006a5dea00 } hitcount: 1 len: 46 | |
1400 | { skbaddr: ffff88002e37a200 } hitcount: 1 len: 44 | |
1401 | { skbaddr: ffff8800a1f32c00 } hitcount: 2 len: 676 | |
1402 | { skbaddr: ffff88000ad52600 } hitcount: 2 len: 107 | |
1403 | { skbaddr: ffff8800a1f91e00 } hitcount: 2 len: 92 | |
1404 | { skbaddr: ffff8800af5a0200 } hitcount: 2 len: 142 | |
1405 | { skbaddr: ffff8800d2bcc600 } hitcount: 2 len: 220 | |
1406 | { skbaddr: ffff8800ba36f500 } hitcount: 2 len: 92 | |
1407 | { skbaddr: ffff8800d021f800 } hitcount: 2 len: 92 | |
1408 | { skbaddr: ffff8800a1f33600 } hitcount: 2 len: 675 | |
1409 | { skbaddr: ffff8800a8bfff00 } hitcount: 3 len: 138 | |
1410 | { skbaddr: ffff8800d62a1300 } hitcount: 3 len: 138 | |
1411 | { skbaddr: ffff88002e37a100 } hitcount: 4 len: 184 | |
1412 | { skbaddr: ffff880064504400 } hitcount: 4 len: 184 | |
1413 | { skbaddr: ffff8800a8bfec00 } hitcount: 4 len: 184 | |
1414 | { skbaddr: ffff88000ad53700 } hitcount: 5 len: 230 | |
1415 | { skbaddr: ffff8800d2bcdb00 } hitcount: 5 len: 196 | |
1416 | { skbaddr: ffff8800a1f90000 } hitcount: 6 len: 276 | |
1417 | { skbaddr: ffff88006a54f900 } hitcount: 6 len: 276 | |
1418 | ||
1419 | Totals: | |
1420 | Hits: 81 | |
1421 | Entries: 42 | |
1422 | Dropped: 0 | |
1423 | # event histogram | |
1424 | # | |
1425 | # trigger info: hist:name=foo:keys=skbaddr.hex:vals=hitcount,len:sort=hitcount:size=2048 [active] | |
1426 | # | |
1427 | ||
1428 | { skbaddr: ffff88000ad53500 } hitcount: 1 len: 46 | |
1429 | { skbaddr: ffff8800af5a1500 } hitcount: 1 len: 76 | |
1430 | { skbaddr: ffff8800d62a1900 } hitcount: 1 len: 46 | |
1431 | { skbaddr: ffff8800d2bccb00 } hitcount: 1 len: 468 | |
1432 | { skbaddr: ffff8800d3c69900 } hitcount: 1 len: 46 | |
1433 | { skbaddr: ffff88009ff09100 } hitcount: 1 len: 52 | |
1434 | { skbaddr: ffff88010f13ab00 } hitcount: 1 len: 168 | |
1435 | { skbaddr: ffff88006a54f400 } hitcount: 1 len: 46 | |
1436 | { skbaddr: ffff8800d2bcc500 } hitcount: 1 len: 260 | |
1437 | { skbaddr: ffff880064505000 } hitcount: 1 len: 46 | |
1438 | { skbaddr: ffff8800baf24e00 } hitcount: 1 len: 32 | |
1439 | { skbaddr: ffff88009fe0ad00 } hitcount: 1 len: 46 | |
1440 | { skbaddr: ffff8800d3edff00 } hitcount: 1 len: 44 | |
1441 | { skbaddr: ffff88009fe0b400 } hitcount: 1 len: 168 | |
1442 | { skbaddr: ffff8800a1c55a00 } hitcount: 1 len: 40 | |
1443 | { skbaddr: ffff8800d2bcd100 } hitcount: 1 len: 40 | |
1444 | { skbaddr: ffff880064505f00 } hitcount: 1 len: 174 | |
1445 | { skbaddr: ffff8800a8bff200 } hitcount: 1 len: 160 | |
1446 | { skbaddr: ffff880044e3cc00 } hitcount: 1 len: 76 | |
1447 | { skbaddr: ffff8800a8bfe700 } hitcount: 1 len: 46 | |
1448 | { skbaddr: ffff8800d2bcdc00 } hitcount: 1 len: 32 | |
1449 | { skbaddr: ffff8800a1f64800 } hitcount: 1 len: 46 | |
1450 | { skbaddr: ffff8800d2bcde00 } hitcount: 1 len: 988 | |
1451 | { skbaddr: ffff88006a5dea00 } hitcount: 1 len: 46 | |
1452 | { skbaddr: ffff88002e37a200 } hitcount: 1 len: 44 | |
1453 | { skbaddr: ffff8800a1f32c00 } hitcount: 2 len: 676 | |
1454 | { skbaddr: ffff88000ad52600 } hitcount: 2 len: 107 | |
1455 | { skbaddr: ffff8800a1f91e00 } hitcount: 2 len: 92 | |
1456 | { skbaddr: ffff8800af5a0200 } hitcount: 2 len: 142 | |
1457 | { skbaddr: ffff8800d2bcc600 } hitcount: 2 len: 220 | |
1458 | { skbaddr: ffff8800ba36f500 } hitcount: 2 len: 92 | |
1459 | { skbaddr: ffff8800d021f800 } hitcount: 2 len: 92 | |
1460 | { skbaddr: ffff8800a1f33600 } hitcount: 2 len: 675 | |
1461 | { skbaddr: ffff8800a8bfff00 } hitcount: 3 len: 138 | |
1462 | { skbaddr: ffff8800d62a1300 } hitcount: 3 len: 138 | |
1463 | { skbaddr: ffff88002e37a100 } hitcount: 4 len: 184 | |
1464 | { skbaddr: ffff880064504400 } hitcount: 4 len: 184 | |
1465 | { skbaddr: ffff8800a8bfec00 } hitcount: 4 len: 184 | |
1466 | { skbaddr: ffff88000ad53700 } hitcount: 5 len: 230 | |
1467 | { skbaddr: ffff8800d2bcdb00 } hitcount: 5 len: 196 | |
1468 | { skbaddr: ffff8800a1f90000 } hitcount: 6 len: 276 | |
1469 | { skbaddr: ffff88006a54f900 } hitcount: 6 len: 276 | |
1470 | ||
1471 | Totals: | |
1472 | Hits: 81 | |
1473 | Entries: 42 | |
1474 | Dropped: 0 | |
1475 | ||
1476 | And here's an example that shows how to combine histogram data from | |
1477 | any two events even if they don't share any 'compatible' fields | |
1478 | other than 'hitcount' and 'stacktrace'. These commands create a | |
ea272257 | 1479 | couple of triggers named 'bar' using those fields:: |
b8df4a36 TZ |
1480 | |
1481 | # echo 'hist:name=bar:key=stacktrace:val=hitcount' > \ | |
1482 | /sys/kernel/debug/tracing/events/sched/sched_process_fork/trigger | |
1483 | # echo 'hist:name=bar:key=stacktrace:val=hitcount' > \ | |
1484 | /sys/kernel/debug/tracing/events/net/netif_rx/trigger | |
1485 | ||
1486 | And displaying the output of either shows some interesting if | |
ea272257 | 1487 | somewhat confusing output:: |
b8df4a36 TZ |
1488 | |
1489 | # cat /sys/kernel/debug/tracing/events/sched/sched_process_fork/hist | |
1490 | # cat /sys/kernel/debug/tracing/events/net/netif_rx/hist | |
1491 | ||
1492 | # event histogram | |
1493 | # | |
1494 | # trigger info: hist:name=bar:keys=stacktrace:vals=hitcount:sort=hitcount:size=2048 [active] | |
1495 | # | |
1496 | ||
1497 | { stacktrace: | |
1498 | _do_fork+0x18e/0x330 | |
1499 | kernel_thread+0x29/0x30 | |
1500 | kthreadd+0x154/0x1b0 | |
1501 | ret_from_fork+0x3f/0x70 | |
1502 | } hitcount: 1 | |
1503 | { stacktrace: | |
1504 | netif_rx_internal+0xb2/0xd0 | |
1505 | netif_rx_ni+0x20/0x70 | |
1506 | dev_loopback_xmit+0xaa/0xd0 | |
1507 | ip_mc_output+0x126/0x240 | |
1508 | ip_local_out_sk+0x31/0x40 | |
1509 | igmp_send_report+0x1e9/0x230 | |
1510 | igmp_timer_expire+0xe9/0x120 | |
1511 | call_timer_fn+0x39/0xf0 | |
1512 | run_timer_softirq+0x1e1/0x290 | |
1513 | __do_softirq+0xfd/0x290 | |
1514 | irq_exit+0x98/0xb0 | |
1515 | smp_apic_timer_interrupt+0x4a/0x60 | |
1516 | apic_timer_interrupt+0x6d/0x80 | |
1517 | cpuidle_enter+0x17/0x20 | |
1518 | call_cpuidle+0x3b/0x60 | |
1519 | cpu_startup_entry+0x22d/0x310 | |
1520 | } hitcount: 1 | |
1521 | { stacktrace: | |
1522 | netif_rx_internal+0xb2/0xd0 | |
1523 | netif_rx_ni+0x20/0x70 | |
1524 | dev_loopback_xmit+0xaa/0xd0 | |
1525 | ip_mc_output+0x17f/0x240 | |
1526 | ip_local_out_sk+0x31/0x40 | |
1527 | ip_send_skb+0x1a/0x50 | |
1528 | udp_send_skb+0x13e/0x270 | |
1529 | udp_sendmsg+0x2bf/0x980 | |
1530 | inet_sendmsg+0x67/0xa0 | |
1531 | sock_sendmsg+0x38/0x50 | |
1532 | SYSC_sendto+0xef/0x170 | |
1533 | SyS_sendto+0xe/0x10 | |
1534 | entry_SYSCALL_64_fastpath+0x12/0x6a | |
1535 | } hitcount: 2 | |
1536 | { stacktrace: | |
1537 | netif_rx_internal+0xb2/0xd0 | |
1538 | netif_rx+0x1c/0x60 | |
1539 | loopback_xmit+0x6c/0xb0 | |
1540 | dev_hard_start_xmit+0x219/0x3a0 | |
1541 | __dev_queue_xmit+0x415/0x4f0 | |
1542 | dev_queue_xmit_sk+0x13/0x20 | |
1543 | ip_finish_output2+0x237/0x340 | |
1544 | ip_finish_output+0x113/0x1d0 | |
1545 | ip_output+0x66/0xc0 | |
1546 | ip_local_out_sk+0x31/0x40 | |
1547 | ip_send_skb+0x1a/0x50 | |
1548 | udp_send_skb+0x16d/0x270 | |
1549 | udp_sendmsg+0x2bf/0x980 | |
1550 | inet_sendmsg+0x67/0xa0 | |
1551 | sock_sendmsg+0x38/0x50 | |
1552 | ___sys_sendmsg+0x14e/0x270 | |
1553 | } hitcount: 76 | |
1554 | { stacktrace: | |
1555 | netif_rx_internal+0xb2/0xd0 | |
1556 | netif_rx+0x1c/0x60 | |
1557 | loopback_xmit+0x6c/0xb0 | |
1558 | dev_hard_start_xmit+0x219/0x3a0 | |
1559 | __dev_queue_xmit+0x415/0x4f0 | |
1560 | dev_queue_xmit_sk+0x13/0x20 | |
1561 | ip_finish_output2+0x237/0x340 | |
1562 | ip_finish_output+0x113/0x1d0 | |
1563 | ip_output+0x66/0xc0 | |
1564 | ip_local_out_sk+0x31/0x40 | |
1565 | ip_send_skb+0x1a/0x50 | |
1566 | udp_send_skb+0x16d/0x270 | |
1567 | udp_sendmsg+0x2bf/0x980 | |
1568 | inet_sendmsg+0x67/0xa0 | |
1569 | sock_sendmsg+0x38/0x50 | |
1570 | ___sys_sendmsg+0x269/0x270 | |
1571 | } hitcount: 77 | |
1572 | { stacktrace: | |
1573 | netif_rx_internal+0xb2/0xd0 | |
1574 | netif_rx+0x1c/0x60 | |
1575 | loopback_xmit+0x6c/0xb0 | |
1576 | dev_hard_start_xmit+0x219/0x3a0 | |
1577 | __dev_queue_xmit+0x415/0x4f0 | |
1578 | dev_queue_xmit_sk+0x13/0x20 | |
1579 | ip_finish_output2+0x237/0x340 | |
1580 | ip_finish_output+0x113/0x1d0 | |
1581 | ip_output+0x66/0xc0 | |
1582 | ip_local_out_sk+0x31/0x40 | |
1583 | ip_send_skb+0x1a/0x50 | |
1584 | udp_send_skb+0x16d/0x270 | |
1585 | udp_sendmsg+0x2bf/0x980 | |
1586 | inet_sendmsg+0x67/0xa0 | |
1587 | sock_sendmsg+0x38/0x50 | |
1588 | SYSC_sendto+0xef/0x170 | |
1589 | } hitcount: 88 | |
1590 | { stacktrace: | |
1591 | _do_fork+0x18e/0x330 | |
1592 | SyS_clone+0x19/0x20 | |
1593 | entry_SYSCALL_64_fastpath+0x12/0x6a | |
1594 | } hitcount: 244 | |
1595 | ||
1596 | Totals: | |
1597 | Hits: 489 | |
1598 | Entries: 7 | |
1599 | Dropped: 0 | |
033cbcee | 1600 | |
033cbcee TZ |
1601 | 2.2 Inter-event hist triggers |
1602 | ----------------------------- | |
1603 | ||
1604 | Inter-event hist triggers are hist triggers that combine values from | |
1605 | one or more other events and create a histogram using that data. Data | |
1606 | from an inter-event histogram can in turn become the source for | |
1607 | further combined histograms, thus providing a chain of related | |
1608 | histograms, which is important for some applications. | |
1609 | ||
1610 | The most important example of an inter-event quantity that can be used | |
1611 | in this manner is latency, which is simply a difference in timestamps | |
1612 | between two events. Although latency is the most important | |
1613 | inter-event quantity, note that because the support is completely | |
1614 | general across the trace event subsystem, any event field can be used | |
1615 | in an inter-event quantity. | |
1616 | ||
1617 | An example of a histogram that combines data from other histograms | |
1618 | into a useful chain would be a 'wakeupswitch latency' histogram that | |
1619 | combines a 'wakeup latency' histogram and a 'switch latency' | |
1620 | histogram. | |
1621 | ||
1622 | Normally, a hist trigger specification consists of a (possibly | |
1623 | compound) key along with one or more numeric values, which are | |
1624 | continually updated sums associated with that key. A histogram | |
1625 | specification in this case consists of individual key and value | |
1626 | specifications that refer to trace event fields associated with a | |
1627 | single event type. | |
1628 | ||
1629 | The inter-event hist trigger extension allows fields from multiple | |
1630 | events to be referenced and combined into a multi-event histogram | |
1631 | specification. In support of this overall goal, a few enabling | |
1632 | features have been added to the hist trigger support: | |
1633 | ||
1634 | - In order to compute an inter-event quantity, a value from one | |
1635 | event needs to saved and then referenced from another event. This | |
1636 | requires the introduction of support for histogram 'variables'. | |
1637 | ||
1638 | - The computation of inter-event quantities and their combination | |
1639 | require some minimal amount of support for applying simple | |
1640 | expressions to variables (+ and -). | |
1641 | ||
1642 | - A histogram consisting of inter-event quantities isn't logically a | |
1643 | histogram on either event (so having the 'hist' file for either | |
1644 | event host the histogram output doesn't really make sense). To | |
1645 | address the idea that the histogram is associated with a | |
1646 | combination of events, support is added allowing the creation of | |
1647 | 'synthetic' events that are events derived from other events. | |
1648 | These synthetic events are full-fledged events just like any other | |
1649 | and can be used as such, as for instance to create the | |
1650 | 'combination' histograms mentioned previously. | |
1651 | ||
1652 | - A set of 'actions' can be associated with histogram entries - | |
1653 | these can be used to generate the previously mentioned synthetic | |
1654 | events, but can also be used for other purposes, such as for | |
1655 | example saving context when a 'max' latency has been hit. | |
1656 | ||
1657 | - Trace events don't have a 'timestamp' associated with them, but | |
1658 | there is an implicit timestamp saved along with an event in the | |
1659 | underlying ftrace ring buffer. This timestamp is now exposed as a | |
1660 | a synthetic field named 'common_timestamp' which can be used in | |
1661 | histograms as if it were any other event field; it isn't an actual | |
1662 | field in the trace format but rather is a synthesized value that | |
1663 | nonetheless can be used as if it were an actual field. By default | |
1664 | it is in units of nanoseconds; appending '.usecs' to a | |
1665 | common_timestamp field changes the units to microseconds. | |
1666 | ||
a4072fe8 TZ |
1667 | A note on inter-event timestamps: If common_timestamp is used in a |
1668 | histogram, the trace buffer is automatically switched over to using | |
1669 | absolute timestamps and the "global" trace clock, in order to avoid | |
1670 | bogus timestamp differences with other clocks that aren't coherent | |
1671 | across CPUs. This can be overridden by specifying one of the other | |
1672 | trace clocks instead, using the "clock=XXX" hist trigger attribute, | |
1673 | where XXX is any of the clocks listed in the tracing/trace_clock | |
1674 | pseudo-file. | |
1675 | ||
1676 | These features are described in more detail in the following sections. | |
033cbcee TZ |
1677 | |
1678 | 2.2.1 Histogram Variables | |
1679 | ------------------------- | |
1680 | ||
1681 | Variables are simply named locations used for saving and retrieving | |
1682 | values between matching events. A 'matching' event is defined as an | |
1683 | event that has a matching key - if a variable is saved for a histogram | |
1684 | entry corresponding to that key, any subsequent event with a matching | |
1685 | key can access that variable. | |
1686 | ||
1687 | A variable's value is normally available to any subsequent event until | |
1688 | it is set to something else by a subsequent event. The one exception | |
1689 | to that rule is that any variable used in an expression is essentially | |
1690 | 'read-once' - once it's used by an expression in a subsequent event, | |
1691 | it's reset to its 'unset' state, which means it can't be used again | |
1692 | unless it's set again. This ensures not only that an event doesn't | |
1693 | use an uninitialized variable in a calculation, but that that variable | |
1694 | is used only once and not for any unrelated subsequent match. | |
1695 | ||
1696 | The basic syntax for saving a variable is to simply prefix a unique | |
1697 | variable name not corresponding to any keyword along with an '=' sign | |
1698 | to any event field. | |
1699 | ||
1700 | Either keys or values can be saved and retrieved in this way. This | |
1701 | creates a variable named 'ts0' for a histogram entry with the key | |
ea272257 | 1702 | 'next_pid':: |
033cbcee TZ |
1703 | |
1704 | # echo 'hist:keys=next_pid:vals=$ts0:ts0=common_timestamp ... >> \ | |
1705 | event/trigger | |
1706 | ||
1707 | The ts0 variable can be accessed by any subsequent event having the | |
1708 | same pid as 'next_pid'. | |
1709 | ||
1710 | Variable references are formed by prepending the variable name with | |
1711 | the '$' sign. Thus for example, the ts0 variable above would be | |
1712 | referenced as '$ts0' in expressions. | |
1713 | ||
1714 | Because 'vals=' is used, the common_timestamp variable value above | |
1715 | will also be summed as a normal histogram value would (though for a | |
1716 | timestamp it makes little sense). | |
1717 | ||
ea272257 | 1718 | The below shows that a key value can also be saved in the same way:: |
033cbcee TZ |
1719 | |
1720 | # echo 'hist:timer_pid=common_pid:key=timer_pid ...' >> event/trigger | |
1721 | ||
1722 | If a variable isn't a key variable or prefixed with 'vals=', the | |
1723 | associated event field will be saved in a variable but won't be summed | |
ea272257 | 1724 | as a value:: |
033cbcee | 1725 | |
064f35a9 | 1726 | # echo 'hist:keys=next_pid:ts1=common_timestamp ...' >> event/trigger |
033cbcee TZ |
1727 | |
1728 | Multiple variables can be assigned at the same time. The below would | |
1729 | result in both ts0 and b being created as variables, with both | |
ea272257 | 1730 | common_timestamp and field1 additionally being summed as values:: |
033cbcee | 1731 | |
064f35a9 | 1732 | # echo 'hist:keys=pid:vals=$ts0,$b:ts0=common_timestamp,b=field1 ...' >> \ |
033cbcee TZ |
1733 | event/trigger |
1734 | ||
1735 | Note that variable assignments can appear either preceding or | |
1736 | following their use. The command below behaves identically to the | |
ea272257 | 1737 | command above:: |
033cbcee | 1738 | |
064f35a9 | 1739 | # echo 'hist:keys=pid:ts0=common_timestamp,b=field1:vals=$ts0,$b ...' >> \ |
033cbcee TZ |
1740 | event/trigger |
1741 | ||
1742 | Any number of variables not bound to a 'vals=' prefix can also be | |
1743 | assigned by simply separating them with colons. Below is the same | |
ea272257 | 1744 | thing but without the values being summed in the histogram:: |
033cbcee | 1745 | |
064f35a9 | 1746 | # echo 'hist:keys=pid:ts0=common_timestamp:b=field1 ...' >> event/trigger |
033cbcee TZ |
1747 | |
1748 | Variables set as above can be referenced and used in expressions on | |
1749 | another event. | |
1750 | ||
ea272257 | 1751 | For example, here's how a latency can be calculated:: |
033cbcee | 1752 | |
064f35a9 JFG |
1753 | # echo 'hist:keys=pid,prio:ts0=common_timestamp ...' >> event1/trigger |
1754 | # echo 'hist:keys=next_pid:wakeup_lat=common_timestamp-$ts0 ...' >> event2/trigger | |
033cbcee | 1755 | |
aea74de4 | 1756 | In the first line above, the event's timestamp is saved into the |
033cbcee TZ |
1757 | variable ts0. In the next line, ts0 is subtracted from the second |
1758 | event's timestamp to produce the latency, which is then assigned into | |
1759 | yet another variable, 'wakeup_lat'. The hist trigger below in turn | |
1760 | makes use of the wakeup_lat variable to compute a combined latency | |
ea272257 | 1761 | using the same key and variable from yet another event:: |
033cbcee | 1762 | |
064f35a9 | 1763 | # echo 'hist:key=pid:wakeupswitch_lat=$wakeup_lat+$switchtime_lat ...' >> event3/trigger |
033cbcee TZ |
1764 | |
1765 | 2.2.2 Synthetic Events | |
1766 | ---------------------- | |
1767 | ||
1768 | Synthetic events are user-defined events generated from hist trigger | |
1769 | variables or fields associated with one or more other events. Their | |
1770 | purpose is to provide a mechanism for displaying data spanning | |
1771 | multiple events consistent with the existing and already familiar | |
1772 | usage for normal events. | |
1773 | ||
1774 | To define a synthetic event, the user writes a simple specification | |
1775 | consisting of the name of the new event along with one or more | |
1776 | variables and their types, which can be any valid field type, | |
1777 | separated by semicolons, to the tracing/synthetic_events file. | |
1778 | ||
1779 | For instance, the following creates a new event named 'wakeup_latency' | |
1780 | with 3 fields: lat, pid, and prio. Each of those fields is simply a | |
ea272257 | 1781 | variable reference to a variable on another event:: |
033cbcee TZ |
1782 | |
1783 | # echo 'wakeup_latency \ | |
1784 | u64 lat; \ | |
1785 | pid_t pid; \ | |
1786 | int prio' >> \ | |
1787 | /sys/kernel/debug/tracing/synthetic_events | |
1788 | ||
1789 | Reading the tracing/synthetic_events file lists all the currently | |
ea272257 | 1790 | defined synthetic events, in this case the event defined above:: |
033cbcee TZ |
1791 | |
1792 | # cat /sys/kernel/debug/tracing/synthetic_events | |
1793 | wakeup_latency u64 lat; pid_t pid; int prio | |
1794 | ||
1795 | An existing synthetic event definition can be removed by prepending | |
ea272257 | 1796 | the command that defined it with a '!':: |
033cbcee TZ |
1797 | |
1798 | # echo '!wakeup_latency u64 lat pid_t pid int prio' >> \ | |
1799 | /sys/kernel/debug/tracing/synthetic_events | |
1800 | ||
1801 | At this point, there isn't yet an actual 'wakeup_latency' event | |
aea74de4 | 1802 | instantiated in the event subsystem - for this to happen, a 'hist |
033cbcee | 1803 | trigger action' needs to be instantiated and bound to actual fields |
064f35a9 JFG |
1804 | and variables defined on other events (see Section 2.2.3 below on |
1805 | how that is done using hist trigger 'onmatch' action). Once that is | |
1806 | done, the 'wakeup_latency' synthetic event instance is created. | |
033cbcee | 1807 | |
ea272257 | 1808 | A histogram can now be defined for the new synthetic event:: |
033cbcee TZ |
1809 | |
1810 | # echo 'hist:keys=pid,prio,lat.log2:sort=pid,lat' >> \ | |
1811 | /sys/kernel/debug/tracing/events/synthetic/wakeup_latency/trigger | |
1812 | ||
1813 | The new event is created under the tracing/events/synthetic/ directory | |
ea272257 | 1814 | and looks and behaves just like any other event:: |
033cbcee TZ |
1815 | |
1816 | # ls /sys/kernel/debug/tracing/events/synthetic/wakeup_latency | |
1817 | enable filter format hist id trigger | |
1818 | ||
1819 | Like any other event, once a histogram is enabled for the event, the | |
1820 | output can be displayed by reading the event's 'hist' file. | |
1821 | ||
5032b381 TZ |
1822 | 2.2.3 Hist trigger 'handlers' and 'actions' |
1823 | ------------------------------------------- | |
033cbcee | 1824 | |
5032b381 TZ |
1825 | A hist trigger 'action' is a function that's executed (in most cases |
1826 | conditionally) whenever a histogram entry is added or updated. | |
033cbcee | 1827 | |
5032b381 TZ |
1828 | When a histogram entry is added or updated, a hist trigger 'handler' |
1829 | is what decides whether the corresponding action is actually invoked | |
1830 | or not. | |
033cbcee | 1831 | |
5032b381 TZ |
1832 | Hist trigger handlers and actions are paired together in the general |
1833 | form: | |
1834 | ||
1835 | <handler>.<action> | |
1836 | ||
1837 | To specify a handler.action pair for a given event, simply specify | |
1838 | that handler.action pair between colons in the hist trigger | |
1839 | specification. | |
1840 | ||
1841 | In theory, any handler can be combined with any action, but in | |
1842 | practice, not every handler.action combination is currently supported; | |
1843 | if a given handler.action combination isn't supported, the hist | |
1844 | trigger will fail with -EINVAL; | |
1845 | ||
fe4ec72c | 1846 | The default 'handler.action' if none is explicitly specified is as it |
5032b381 TZ |
1847 | always has been, to simply update the set of values associated with an |
1848 | entry. Some applications, however, may want to perform additional | |
1849 | actions at that point, such as generate another event, or compare and | |
1850 | save a maximum. | |
1851 | ||
1852 | The supported handlers and actions are listed below, and each is | |
1853 | described in more detail in the following paragraphs, in the context | |
1854 | of descriptions of some common and useful handler.action combinations. | |
1855 | ||
1856 | The available handlers are: | |
1857 | ||
1858 | - onmatch(matching.event) - invoke action on any addition or update | |
1859 | - onmax(var) - invoke action if var exceeds current max | |
ff0d35e2 | 1860 | - onchange(var) - invoke action if var changes |
5032b381 TZ |
1861 | |
1862 | The available actions are: | |
1863 | ||
e91eefd7 | 1864 | - trace(<synthetic_event_name>,param list) - generate synthetic event |
5032b381 | 1865 | - save(field,...) - save current event fields |
fd451a3d | 1866 | - snapshot() - snapshot the trace buffer |
5032b381 TZ |
1867 | |
1868 | The following commonly-used handler.action pairs are available: | |
033cbcee | 1869 | |
e91eefd7 | 1870 | - onmatch(matching.event).trace(<synthetic_event_name>,param list) |
033cbcee | 1871 | |
e91eefd7 TZ |
1872 | The 'onmatch(matching.event).trace(<synthetic_event_name>,param |
1873 | list)' hist trigger action is invoked whenever an event matches | |
1874 | and the histogram entry would be added or updated. It causes the | |
1875 | named synthetic event to be generated with the values given in the | |
033cbcee TZ |
1876 | 'param list'. The result is the generation of a synthetic event |
1877 | that consists of the values contained in those variables at the | |
e91eefd7 TZ |
1878 | time the invoking event was hit. For example, if the synthetic |
1879 | event name is 'wakeup_latency', a wakeup_latency event is | |
1880 | generated using onmatch(event).trace(wakeup_latency,arg1,arg2). | |
1881 | ||
1882 | There is also an equivalent alternative form available for | |
1883 | generating synthetic events. In this form, the synthetic event | |
1884 | name is used as if it were a function name. For example, using | |
1885 | the 'wakeup_latency' synthetic event name again, the | |
1886 | wakeup_latency event would be generated by invoking it as if it | |
1887 | were a function call, with the event field values passed in as | |
1888 | arguments: onmatch(event).wakeup_latency(arg1,arg2). The syntax | |
1889 | for this form is: | |
1890 | ||
1891 | onmatch(matching.event).<synthetic_event_name>(param list) | |
1892 | ||
1893 | In either case, the 'param list' consists of one or more | |
1894 | parameters which may be either variables or fields defined on | |
1895 | either the 'matching.event' or the target event. The variables or | |
1896 | fields specified in the param list may be either fully-qualified | |
1897 | or unqualified. If a variable is specified as unqualified, it | |
1898 | must be unique between the two events. A field name used as a | |
1899 | param can be unqualified if it refers to the target event, but | |
1900 | must be fully qualified if it refers to the matching event. A | |
1901 | fully-qualified name is of the form 'system.event_name.$var_name' | |
1902 | or 'system.event_name.field'. | |
033cbcee TZ |
1903 | |
1904 | The 'matching.event' specification is simply the fully qualified | |
1905 | event name of the event that matches the target event for the | |
39a39d5b TS |
1906 | onmatch() functionality, in the form 'system.event_name'. Histogram |
1907 | keys of both events are compared to find if events match. In case | |
1908 | multiple histogram keys are used, they all must match in the specified | |
1909 | order. | |
033cbcee TZ |
1910 | |
1911 | Finally, the number and type of variables/fields in the 'param | |
1912 | list' must match the number and types of the fields in the | |
1913 | synthetic event being generated. | |
1914 | ||
1915 | As an example the below defines a simple synthetic event and uses | |
1916 | a variable defined on the sched_wakeup_new event as a parameter | |
1917 | when invoking the synthetic event. Here we define the synthetic | |
ea272257 | 1918 | event:: |
033cbcee | 1919 | |
ea272257 MCC |
1920 | # echo 'wakeup_new_test pid_t pid' >> \ |
1921 | /sys/kernel/debug/tracing/synthetic_events | |
033cbcee | 1922 | |
ea272257 MCC |
1923 | # cat /sys/kernel/debug/tracing/synthetic_events |
1924 | wakeup_new_test pid_t pid | |
033cbcee TZ |
1925 | |
1926 | The following hist trigger both defines the missing testpid | |
1927 | variable and specifies an onmatch() action that generates a | |
1928 | wakeup_new_test synthetic event whenever a sched_wakeup_new event | |
1929 | occurs, which because of the 'if comm == "cyclictest"' filter only | |
ea272257 | 1930 | happens when the executable is cyclictest:: |
033cbcee | 1931 | |
ea272257 MCC |
1932 | # echo 'hist:keys=$testpid:testpid=pid:onmatch(sched.sched_wakeup_new).\ |
1933 | wakeup_new_test($testpid) if comm=="cyclictest"' >> \ | |
1934 | /sys/kernel/debug/tracing/events/sched/sched_wakeup_new/trigger | |
033cbcee | 1935 | |
e91eefd7 TZ |
1936 | Or, equivalently, using the 'trace' keyword syntax: |
1937 | ||
1938 | # echo 'hist:keys=$testpid:testpid=pid:onmatch(sched.sched_wakeup_new).\ | |
1939 | trace(wakeup_new_test,$testpid) if comm=="cyclictest"' >> \ | |
1940 | /sys/kernel/debug/tracing/events/sched/sched_wakeup_new/trigger | |
1941 | ||
033cbcee TZ |
1942 | Creating and displaying a histogram based on those events is now |
1943 | just a matter of using the fields and new synthetic event in the | |
ea272257 | 1944 | tracing/events/synthetic directory, as usual:: |
033cbcee | 1945 | |
ea272257 MCC |
1946 | # echo 'hist:keys=pid:sort=pid' >> \ |
1947 | /sys/kernel/debug/tracing/events/synthetic/wakeup_new_test/trigger | |
033cbcee TZ |
1948 | |
1949 | Running 'cyclictest' should cause wakeup_new events to generate | |
1950 | wakeup_new_test synthetic events which should result in histogram | |
ea272257 | 1951 | output in the wakeup_new_test event's hist file:: |
033cbcee | 1952 | |
ea272257 | 1953 | # cat /sys/kernel/debug/tracing/events/synthetic/wakeup_new_test/hist |
033cbcee TZ |
1954 | |
1955 | A more typical usage would be to use two events to calculate a | |
1956 | latency. The following example uses a set of hist triggers to | |
ea272257 | 1957 | produce a 'wakeup_latency' histogram. |
033cbcee | 1958 | |
ea272257 | 1959 | First, we define a 'wakeup_latency' synthetic event:: |
033cbcee | 1960 | |
ea272257 MCC |
1961 | # echo 'wakeup_latency u64 lat; pid_t pid; int prio' >> \ |
1962 | /sys/kernel/debug/tracing/synthetic_events | |
033cbcee TZ |
1963 | |
1964 | Next, we specify that whenever we see a sched_waking event for a | |
ea272257 | 1965 | cyclictest thread, save the timestamp in a 'ts0' variable:: |
033cbcee | 1966 | |
ea272257 MCC |
1967 | # echo 'hist:keys=$saved_pid:saved_pid=pid:ts0=common_timestamp.usecs \ |
1968 | if comm=="cyclictest"' >> \ | |
1969 | /sys/kernel/debug/tracing/events/sched/sched_waking/trigger | |
033cbcee TZ |
1970 | |
1971 | Then, when the corresponding thread is actually scheduled onto the | |
39a39d5b TS |
1972 | CPU by a sched_switch event (saved_pid matches next_pid), calculate |
1973 | the latency and use that along with another variable and an event field | |
1974 | to generate a wakeup_latency synthetic event:: | |
033cbcee | 1975 | |
ea272257 MCC |
1976 | # echo 'hist:keys=next_pid:wakeup_lat=common_timestamp.usecs-$ts0:\ |
1977 | onmatch(sched.sched_waking).wakeup_latency($wakeup_lat,\ | |
1978 | $saved_pid,next_prio) if next_comm=="cyclictest"' >> \ | |
1979 | /sys/kernel/debug/tracing/events/sched/sched_switch/trigger | |
033cbcee TZ |
1980 | |
1981 | We also need to create a histogram on the wakeup_latency synthetic | |
ea272257 | 1982 | event in order to aggregate the generated synthetic event data:: |
033cbcee | 1983 | |
ea272257 MCC |
1984 | # echo 'hist:keys=pid,prio,lat:sort=pid,lat' >> \ |
1985 | /sys/kernel/debug/tracing/events/synthetic/wakeup_latency/trigger | |
033cbcee TZ |
1986 | |
1987 | Finally, once we've run cyclictest to actually generate some | |
1988 | events, we can see the output by looking at the wakeup_latency | |
ea272257 | 1989 | synthetic event's hist file:: |
033cbcee | 1990 | |
ea272257 | 1991 | # cat /sys/kernel/debug/tracing/events/synthetic/wakeup_latency/hist |
033cbcee TZ |
1992 | |
1993 | - onmax(var).save(field,.. .) | |
1994 | ||
1995 | The 'onmax(var).save(field,...)' hist trigger action is invoked | |
1996 | whenever the value of 'var' associated with a histogram entry | |
1997 | exceeds the current maximum contained in that variable. | |
1998 | ||
1999 | The end result is that the trace event fields specified as the | |
2000 | onmax.save() params will be saved if 'var' exceeds the current | |
2001 | maximum for that hist trigger entry. This allows context from the | |
2002 | event that exhibited the new maximum to be saved for later | |
2003 | reference. When the histogram is displayed, additional fields | |
2004 | displaying the saved values will be printed. | |
2005 | ||
2006 | As an example the below defines a couple of hist triggers, one for | |
2007 | sched_waking and another for sched_switch, keyed on pid. Whenever | |
2008 | a sched_waking occurs, the timestamp is saved in the entry | |
2009 | corresponding to the current pid, and when the scheduler switches | |
2010 | back to that pid, the timestamp difference is calculated. If the | |
2011 | resulting latency, stored in wakeup_lat, exceeds the current | |
2012 | maximum latency, the values specified in the save() fields are | |
ea272257 | 2013 | recorded:: |
033cbcee | 2014 | |
ea272257 MCC |
2015 | # echo 'hist:keys=pid:ts0=common_timestamp.usecs \ |
2016 | if comm=="cyclictest"' >> \ | |
2017 | /sys/kernel/debug/tracing/events/sched/sched_waking/trigger | |
033cbcee | 2018 | |
ea272257 MCC |
2019 | # echo 'hist:keys=next_pid:\ |
2020 | wakeup_lat=common_timestamp.usecs-$ts0:\ | |
2021 | onmax($wakeup_lat).save(next_comm,prev_pid,prev_prio,prev_comm) \ | |
2022 | if next_comm=="cyclictest"' >> \ | |
2023 | /sys/kernel/debug/tracing/events/sched/sched_switch/trigger | |
033cbcee TZ |
2024 | |
2025 | When the histogram is displayed, the max value and the saved | |
2026 | values corresponding to the max are displayed following the rest | |
ea272257 | 2027 | of the fields:: |
033cbcee | 2028 | |
ea272257 MCC |
2029 | # cat /sys/kernel/debug/tracing/events/sched/sched_switch/hist |
2030 | { next_pid: 2255 } hitcount: 239 | |
2031 | common_timestamp-ts0: 0 | |
2032 | max: 27 | |
2033 | next_comm: cyclictest | |
2034 | prev_pid: 0 prev_prio: 120 prev_comm: swapper/1 | |
033cbcee | 2035 | |
ea272257 MCC |
2036 | { next_pid: 2256 } hitcount: 2355 |
2037 | common_timestamp-ts0: 0 | |
2038 | max: 49 next_comm: cyclictest | |
2039 | prev_pid: 0 prev_prio: 120 prev_comm: swapper/0 | |
033cbcee | 2040 | |
ea272257 MCC |
2041 | Totals: |
2042 | Hits: 12970 | |
2043 | Entries: 2 | |
2044 | Dropped: 0 | |
d3439f9d | 2045 | |
fd451a3d TZ |
2046 | - onmax(var).snapshot() |
2047 | ||
2048 | The 'onmax(var).snapshot()' hist trigger action is invoked | |
2049 | whenever the value of 'var' associated with a histogram entry | |
2050 | exceeds the current maximum contained in that variable. | |
2051 | ||
2052 | The end result is that a global snapshot of the trace buffer will | |
2053 | be saved in the tracing/snapshot file if 'var' exceeds the current | |
2054 | maximum for any hist trigger entry. | |
2055 | ||
2056 | Note that in this case the maximum is a global maximum for the | |
2057 | current trace instance, which is the maximum across all buckets of | |
2058 | the histogram. The key of the specific trace event that caused | |
2059 | the global maximum and the global maximum itself are displayed, | |
2060 | along with a message stating that a snapshot has been taken and | |
2061 | where to find it. The user can use the key information displayed | |
2062 | to locate the corresponding bucket in the histogram for even more | |
2063 | detail. | |
2064 | ||
2065 | As an example the below defines a couple of hist triggers, one for | |
2066 | sched_waking and another for sched_switch, keyed on pid. Whenever | |
2067 | a sched_waking event occurs, the timestamp is saved in the entry | |
2068 | corresponding to the current pid, and when the scheduler switches | |
2069 | back to that pid, the timestamp difference is calculated. If the | |
2070 | resulting latency, stored in wakeup_lat, exceeds the current | |
2071 | maximum latency, a snapshot is taken. As part of the setup, all | |
2072 | the scheduler events are also enabled, which are the events that | |
2073 | will show up in the snapshot when it is taken at some point: | |
2074 | ||
2075 | # echo 1 > /sys/kernel/debug/tracing/events/sched/enable | |
2076 | ||
2077 | # echo 'hist:keys=pid:ts0=common_timestamp.usecs \ | |
2078 | if comm=="cyclictest"' >> \ | |
2079 | /sys/kernel/debug/tracing/events/sched/sched_waking/trigger | |
2080 | ||
2081 | # echo 'hist:keys=next_pid:wakeup_lat=common_timestamp.usecs-$ts0: \ | |
2082 | onmax($wakeup_lat).save(next_prio,next_comm,prev_pid,prev_prio, \ | |
2083 | prev_comm):onmax($wakeup_lat).snapshot() \ | |
2084 | if next_comm=="cyclictest"' >> \ | |
2085 | /sys/kernel/debug/tracing/events/sched/sched_switch/trigger | |
2086 | ||
2087 | When the histogram is displayed, for each bucket the max value | |
2088 | and the saved values corresponding to the max are displayed | |
2089 | following the rest of the fields. | |
2090 | ||
fe4ec72c | 2091 | If a snapshot was taken, there is also a message indicating that, |
fd451a3d TZ |
2092 | along with the value and event that triggered the global maximum: |
2093 | ||
2094 | # cat /sys/kernel/debug/tracing/events/sched/sched_switch/hist | |
2095 | { next_pid: 2101 } hitcount: 200 | |
2096 | max: 52 next_prio: 120 next_comm: cyclictest \ | |
2097 | prev_pid: 0 prev_prio: 120 prev_comm: swapper/6 | |
2098 | ||
2099 | { next_pid: 2103 } hitcount: 1326 | |
2100 | max: 572 next_prio: 19 next_comm: cyclictest \ | |
2101 | prev_pid: 0 prev_prio: 120 prev_comm: swapper/1 | |
2102 | ||
2103 | { next_pid: 2102 } hitcount: 1982 \ | |
2104 | max: 74 next_prio: 19 next_comm: cyclictest \ | |
2105 | prev_pid: 0 prev_prio: 120 prev_comm: swapper/5 | |
2106 | ||
2107 | Snapshot taken (see tracing/snapshot). Details: | |
2108 | triggering value { onmax($wakeup_lat) }: 572 \ | |
2109 | triggered by event with key: { next_pid: 2103 } | |
2110 | ||
2111 | Totals: | |
2112 | Hits: 3508 | |
2113 | Entries: 3 | |
2114 | Dropped: 0 | |
2115 | ||
2116 | In the above case, the event that triggered the global maximum has | |
2117 | the key with next_pid == 2103. If you look at the bucket that has | |
2118 | 2103 as the key, you'll find the additional values save()'d along | |
2119 | with the local maximum for that bucket, which should be the same | |
2120 | as the global maximum (since that was the same value that | |
2121 | triggered the global snapshot). | |
2122 | ||
2123 | And finally, looking at the snapshot data should show at or near | |
2124 | the end the event that triggered the snapshot (in this case you | |
2125 | can verify the timestamps between the sched_waking and | |
2126 | sched_switch events, which should match the time displayed in the | |
3df5ffd2 MCC |
2127 | global maximum):: |
2128 | ||
2129 | # cat /sys/kernel/debug/tracing/snapshot | |
2130 | ||
2131 | <...>-2103 [005] d..3 309.873125: sched_switch: prev_comm=cyclictest prev_pid=2103 prev_prio=19 prev_state=D ==> next_comm=swapper/5 next_pid=0 next_prio=120 | |
2132 | <idle>-0 [005] d.h3 309.873611: sched_waking: comm=cyclictest pid=2102 prio=19 target_cpu=005 | |
2133 | <idle>-0 [005] dNh4 309.873613: sched_wakeup: comm=cyclictest pid=2102 prio=19 target_cpu=005 | |
2134 | <idle>-0 [005] d..3 309.873616: sched_switch: prev_comm=swapper/5 prev_pid=0 prev_prio=120 prev_state=S ==> next_comm=cyclictest next_pid=2102 next_prio=19 | |
2135 | <...>-2102 [005] d..3 309.873625: sched_switch: prev_comm=cyclictest prev_pid=2102 prev_prio=19 prev_state=D ==> next_comm=swapper/5 next_pid=0 next_prio=120 | |
2136 | <idle>-0 [005] d.h3 309.874624: sched_waking: comm=cyclictest pid=2102 prio=19 target_cpu=005 | |
2137 | <idle>-0 [005] dNh4 309.874626: sched_wakeup: comm=cyclictest pid=2102 prio=19 target_cpu=005 | |
2138 | <idle>-0 [005] dNh3 309.874628: sched_waking: comm=cyclictest pid=2103 prio=19 target_cpu=005 | |
2139 | <idle>-0 [005] dNh4 309.874630: sched_wakeup: comm=cyclictest pid=2103 prio=19 target_cpu=005 | |
2140 | <idle>-0 [005] d..3 309.874633: sched_switch: prev_comm=swapper/5 prev_pid=0 prev_prio=120 prev_state=S ==> next_comm=cyclictest next_pid=2102 next_prio=19 | |
2141 | <idle>-0 [004] d.h3 309.874757: sched_waking: comm=gnome-terminal- pid=1699 prio=120 target_cpu=004 | |
2142 | <idle>-0 [004] dNh4 309.874762: sched_wakeup: comm=gnome-terminal- pid=1699 prio=120 target_cpu=004 | |
2143 | <idle>-0 [004] d..3 309.874766: sched_switch: prev_comm=swapper/4 prev_pid=0 prev_prio=120 prev_state=S ==> next_comm=gnome-terminal- next_pid=1699 next_prio=120 | |
2144 | gnome-terminal--1699 [004] d.h2 309.874941: sched_stat_runtime: comm=gnome-terminal- pid=1699 runtime=180706 [ns] vruntime=1126870572 [ns] | |
2145 | <idle>-0 [003] d.s4 309.874956: sched_waking: comm=rcu_sched pid=9 prio=120 target_cpu=007 | |
2146 | <idle>-0 [003] d.s5 309.874960: sched_wake_idle_without_ipi: cpu=7 | |
2147 | <idle>-0 [003] d.s5 309.874961: sched_wakeup: comm=rcu_sched pid=9 prio=120 target_cpu=007 | |
2148 | <idle>-0 [007] d..3 309.874963: sched_switch: prev_comm=swapper/7 prev_pid=0 prev_prio=120 prev_state=S ==> next_comm=rcu_sched next_pid=9 next_prio=120 | |
2149 | rcu_sched-9 [007] d..3 309.874973: sched_stat_runtime: comm=rcu_sched pid=9 runtime=13646 [ns] vruntime=22531430286 [ns] | |
2150 | rcu_sched-9 [007] d..3 309.874978: sched_switch: prev_comm=rcu_sched prev_pid=9 prev_prio=120 prev_state=R+ ==> next_comm=swapper/7 next_pid=0 next_prio=120 | |
2151 | <...>-2102 [005] d..4 309.874994: sched_migrate_task: comm=cyclictest pid=2103 prio=19 orig_cpu=5 dest_cpu=1 | |
2152 | <...>-2102 [005] d..4 309.875185: sched_wake_idle_without_ipi: cpu=1 | |
2153 | <idle>-0 [001] d..3 309.875200: sched_switch: prev_comm=swapper/1 prev_pid=0 prev_prio=120 prev_state=S ==> next_comm=cyclictest next_pid=2103 next_prio=19 | |
fd451a3d | 2154 | |
ff0d35e2 TZ |
2155 | - onchange(var).save(field,.. .) |
2156 | ||
2157 | The 'onchange(var).save(field,...)' hist trigger action is invoked | |
2158 | whenever the value of 'var' associated with a histogram entry | |
2159 | changes. | |
2160 | ||
2161 | The end result is that the trace event fields specified as the | |
2162 | onchange.save() params will be saved if 'var' changes for that | |
2163 | hist trigger entry. This allows context from the event that | |
2164 | changed the value to be saved for later reference. When the | |
2165 | histogram is displayed, additional fields displaying the saved | |
2166 | values will be printed. | |
2167 | ||
2168 | - onchange(var).snapshot() | |
2169 | ||
2170 | The 'onchange(var).snapshot()' hist trigger action is invoked | |
2171 | whenever the value of 'var' associated with a histogram entry | |
2172 | changes. | |
2173 | ||
2174 | The end result is that a global snapshot of the trace buffer will | |
2175 | be saved in the tracing/snapshot file if 'var' changes for any | |
2176 | hist trigger entry. | |
2177 | ||
2178 | Note that in this case the changed value is a global variable | |
fe4ec72c | 2179 | associated with current trace instance. The key of the specific |
ff0d35e2 TZ |
2180 | trace event that caused the value to change and the global value |
2181 | itself are displayed, along with a message stating that a snapshot | |
2182 | has been taken and where to find it. The user can use the key | |
2183 | information displayed to locate the corresponding bucket in the | |
2184 | histogram for even more detail. | |
2185 | ||
2186 | As an example the below defines a hist trigger on the tcp_probe | |
2187 | event, keyed on dport. Whenever a tcp_probe event occurs, the | |
2188 | cwnd field is checked against the current value stored in the | |
2189 | $cwnd variable. If the value has changed, a snapshot is taken. | |
2190 | As part of the setup, all the scheduler and tcp events are also | |
2191 | enabled, which are the events that will show up in the snapshot | |
2192 | when it is taken at some point: | |
2193 | ||
2194 | # echo 1 > /sys/kernel/debug/tracing/events/sched/enable | |
2195 | # echo 1 > /sys/kernel/debug/tracing/events/tcp/enable | |
2196 | ||
2197 | # echo 'hist:keys=dport:cwnd=snd_cwnd: \ | |
2198 | onchange($cwnd).save(snd_wnd,srtt,rcv_wnd): \ | |
2199 | onchange($cwnd).snapshot()' >> \ | |
2200 | /sys/kernel/debug/tracing/events/tcp/tcp_probe/trigger | |
2201 | ||
2202 | When the histogram is displayed, for each bucket the tracked value | |
2203 | and the saved values corresponding to that value are displayed | |
2204 | following the rest of the fields. | |
2205 | ||
fe4ec72c | 2206 | If a snapshot was taken, there is also a message indicating that, |
3df5ffd2 MCC |
2207 | along with the value and event that triggered the snapshot:: |
2208 | ||
2209 | # cat /sys/kernel/debug/tracing/events/tcp/tcp_probe/hist | |
ff0d35e2 | 2210 | |
ff0d35e2 TZ |
2211 | { dport: 1521 } hitcount: 8 |
2212 | changed: 10 snd_wnd: 35456 srtt: 154262 rcv_wnd: 42112 | |
2213 | ||
2214 | { dport: 80 } hitcount: 23 | |
2215 | changed: 10 snd_wnd: 28960 srtt: 19604 rcv_wnd: 29312 | |
2216 | ||
2217 | { dport: 9001 } hitcount: 172 | |
2218 | changed: 10 snd_wnd: 48384 srtt: 260444 rcv_wnd: 55168 | |
2219 | ||
2220 | { dport: 443 } hitcount: 211 | |
2221 | changed: 10 snd_wnd: 26960 srtt: 17379 rcv_wnd: 28800 | |
2222 | ||
3df5ffd2 MCC |
2223 | Snapshot taken (see tracing/snapshot). Details:: |
2224 | ||
ff0d35e2 TZ |
2225 | triggering value { onchange($cwnd) }: 10 |
2226 | triggered by event with key: { dport: 80 } | |
2227 | ||
3df5ffd2 MCC |
2228 | Totals: |
2229 | Hits: 414 | |
2230 | Entries: 4 | |
2231 | Dropped: 0 | |
ff0d35e2 TZ |
2232 | |
2233 | In the above case, the event that triggered the snapshot has the | |
2234 | key with dport == 80. If you look at the bucket that has 80 as | |
2235 | the key, you'll find the additional values save()'d along with the | |
2236 | changed value for that bucket, which should be the same as the | |
2237 | global changed value (since that was the same value that triggered | |
2238 | the global snapshot). | |
2239 | ||
2240 | And finally, looking at the snapshot data should show at or near | |
3df5ffd2 MCC |
2241 | the end the event that triggered the snapshot:: |
2242 | ||
2243 | # cat /sys/kernel/debug/tracing/snapshot | |
2244 | ||
2245 | gnome-shell-1261 [006] dN.3 49.823113: sched_stat_runtime: comm=gnome-shell pid=1261 runtime=49347 [ns] vruntime=1835730389 [ns] | |
2246 | kworker/u16:4-773 [003] d..3 49.823114: sched_switch: prev_comm=kworker/u16:4 prev_pid=773 prev_prio=120 prev_state=R+ ==> next_comm=kworker/3:2 next_pid=135 next_prio=120 | |
2247 | gnome-shell-1261 [006] d..3 49.823114: sched_switch: prev_comm=gnome-shell prev_pid=1261 prev_prio=120 prev_state=R+ ==> next_comm=kworker/6:2 next_pid=387 next_prio=120 | |
2248 | kworker/3:2-135 [003] d..3 49.823118: sched_stat_runtime: comm=kworker/3:2 pid=135 runtime=5339 [ns] vruntime=17815800388 [ns] | |
2249 | kworker/6:2-387 [006] d..3 49.823120: sched_stat_runtime: comm=kworker/6:2 pid=387 runtime=9594 [ns] vruntime=14589605367 [ns] | |
2250 | kworker/6:2-387 [006] d..3 49.823122: sched_switch: prev_comm=kworker/6:2 prev_pid=387 prev_prio=120 prev_state=R+ ==> next_comm=gnome-shell next_pid=1261 next_prio=120 | |
2251 | kworker/3:2-135 [003] d..3 49.823123: sched_switch: prev_comm=kworker/3:2 prev_pid=135 prev_prio=120 prev_state=T ==> next_comm=swapper/3 next_pid=0 next_prio=120 | |
2252 | <idle>-0 [004] ..s7 49.823798: tcp_probe: src=10.0.0.10:54326 dest=23.215.104.193:80 mark=0x0 length=32 snd_nxt=0xe3ae2ff5 snd_una=0xe3ae2ecd snd_cwnd=10 ssthresh=2147483647 snd_wnd=28960 srtt=19604 rcv_wnd=29312 | |
ff0d35e2 | 2253 | |
d3439f9d SRV |
2254 | 3. User space creating a trigger |
2255 | -------------------------------- | |
2256 | ||
2257 | Writing into /sys/kernel/tracing/trace_marker writes into the ftrace | |
2258 | ring buffer. This can also act like an event, by writing into the trigger | |
2259 | file located in /sys/kernel/tracing/events/ftrace/print/ | |
2260 | ||
2261 | Modifying cyclictest to write into the trace_marker file before it sleeps | |
ea272257 | 2262 | and after it wakes up, something like this:: |
d3439f9d | 2263 | |
ea272257 MCC |
2264 | static void traceputs(char *str) |
2265 | { | |
d3439f9d SRV |
2266 | /* tracemark_fd is the trace_marker file descriptor */ |
2267 | if (tracemark_fd < 0) | |
2268 | return; | |
2269 | /* write the tracemark message */ | |
2270 | write(tracemark_fd, str, strlen(str)); | |
ea272257 | 2271 | } |
d3439f9d | 2272 | |
ea272257 | 2273 | And later add something like:: |
d3439f9d SRV |
2274 | |
2275 | traceputs("start"); | |
2276 | clock_nanosleep(...); | |
2277 | traceputs("end"); | |
2278 | ||
ea272257 | 2279 | We can make a histogram from this:: |
d3439f9d SRV |
2280 | |
2281 | # cd /sys/kernel/tracing | |
2282 | # echo 'latency u64 lat' > synthetic_events | |
2283 | # echo 'hist:keys=common_pid:ts0=common_timestamp.usecs if buf == "start"' > events/ftrace/print/trigger | |
2284 | # echo 'hist:keys=common_pid:lat=common_timestamp.usecs-$ts0:onmatch(ftrace.print).latency($lat) if buf == "end"' >> events/ftrace/print/trigger | |
2285 | # echo 'hist:keys=lat,common_pid:sort=lat' > events/synthetic/latency/trigger | |
2286 | ||
2287 | The above created a synthetic event called "latency" and two histograms | |
2288 | against the trace_marker, one gets triggered when "start" is written into the | |
2289 | trace_marker file and the other when "end" is written. If the pids match, then | |
2290 | it will call the "latency" synthetic event with the calculated latency as its | |
2291 | parameter. Finally, a histogram is added to the latency synthetic event to | |
2292 | record the calculated latency along with the pid. | |
2293 | ||
ea272257 | 2294 | Now running cyclictest with:: |
d3439f9d SRV |
2295 | |
2296 | # ./cyclictest -p80 -d0 -i250 -n -a -t --tracemark -b 1000 | |
2297 | ||
2298 | -p80 : run threads at priority 80 | |
2299 | -d0 : have all threads run at the same interval | |
2300 | -i250 : start the interval at 250 microseconds (all threads will do this) | |
2301 | -n : sleep with nanosleep | |
2302 | -a : affine all threads to a separate CPU | |
2303 | -t : one thread per available CPU | |
2304 | --tracemark : enable trace mark writing | |
2305 | -b 1000 : stop if any latency is greater than 1000 microseconds | |
2306 | ||
2307 | Note, the -b 1000 is used just to make --tracemark available. | |
2308 | ||
ea272257 | 2309 | Then we can see the histogram created by this with:: |
d3439f9d SRV |
2310 | |
2311 | # cat events/synthetic/latency/hist | |
ea272257 MCC |
2312 | # event histogram |
2313 | # | |
2314 | # trigger info: hist:keys=lat,common_pid:vals=hitcount:sort=lat:size=2048 [active] | |
2315 | # | |
2316 | ||
2317 | { lat: 107, common_pid: 2039 } hitcount: 1 | |
2318 | { lat: 122, common_pid: 2041 } hitcount: 1 | |
2319 | { lat: 166, common_pid: 2039 } hitcount: 1 | |
2320 | { lat: 174, common_pid: 2039 } hitcount: 1 | |
2321 | { lat: 194, common_pid: 2041 } hitcount: 1 | |
2322 | { lat: 196, common_pid: 2036 } hitcount: 1 | |
2323 | { lat: 197, common_pid: 2038 } hitcount: 1 | |
2324 | { lat: 198, common_pid: 2039 } hitcount: 1 | |
2325 | { lat: 199, common_pid: 2039 } hitcount: 1 | |
2326 | { lat: 200, common_pid: 2041 } hitcount: 1 | |
2327 | { lat: 201, common_pid: 2039 } hitcount: 2 | |
2328 | { lat: 202, common_pid: 2038 } hitcount: 1 | |
2329 | { lat: 202, common_pid: 2043 } hitcount: 1 | |
2330 | { lat: 203, common_pid: 2039 } hitcount: 1 | |
2331 | { lat: 203, common_pid: 2036 } hitcount: 1 | |
2332 | { lat: 203, common_pid: 2041 } hitcount: 1 | |
2333 | { lat: 206, common_pid: 2038 } hitcount: 2 | |
2334 | { lat: 207, common_pid: 2039 } hitcount: 1 | |
2335 | { lat: 207, common_pid: 2036 } hitcount: 1 | |
2336 | { lat: 208, common_pid: 2040 } hitcount: 1 | |
2337 | { lat: 209, common_pid: 2043 } hitcount: 1 | |
2338 | { lat: 210, common_pid: 2039 } hitcount: 1 | |
2339 | { lat: 211, common_pid: 2039 } hitcount: 4 | |
2340 | { lat: 212, common_pid: 2043 } hitcount: 1 | |
2341 | { lat: 212, common_pid: 2039 } hitcount: 2 | |
2342 | { lat: 213, common_pid: 2039 } hitcount: 1 | |
2343 | { lat: 214, common_pid: 2038 } hitcount: 1 | |
2344 | { lat: 214, common_pid: 2039 } hitcount: 2 | |
2345 | { lat: 214, common_pid: 2042 } hitcount: 1 | |
2346 | { lat: 215, common_pid: 2039 } hitcount: 1 | |
2347 | { lat: 217, common_pid: 2036 } hitcount: 1 | |
2348 | { lat: 217, common_pid: 2040 } hitcount: 1 | |
2349 | { lat: 217, common_pid: 2039 } hitcount: 1 | |
2350 | { lat: 218, common_pid: 2039 } hitcount: 6 | |
2351 | { lat: 219, common_pid: 2039 } hitcount: 9 | |
2352 | { lat: 220, common_pid: 2039 } hitcount: 11 | |
2353 | { lat: 221, common_pid: 2039 } hitcount: 5 | |
2354 | { lat: 221, common_pid: 2042 } hitcount: 1 | |
2355 | { lat: 222, common_pid: 2039 } hitcount: 7 | |
2356 | { lat: 223, common_pid: 2036 } hitcount: 1 | |
2357 | { lat: 223, common_pid: 2039 } hitcount: 3 | |
2358 | { lat: 224, common_pid: 2039 } hitcount: 4 | |
2359 | { lat: 224, common_pid: 2037 } hitcount: 1 | |
2360 | { lat: 224, common_pid: 2036 } hitcount: 2 | |
2361 | { lat: 225, common_pid: 2039 } hitcount: 5 | |
2362 | { lat: 225, common_pid: 2042 } hitcount: 1 | |
2363 | { lat: 226, common_pid: 2039 } hitcount: 7 | |
2364 | { lat: 226, common_pid: 2036 } hitcount: 4 | |
2365 | { lat: 227, common_pid: 2039 } hitcount: 6 | |
2366 | { lat: 227, common_pid: 2036 } hitcount: 12 | |
2367 | { lat: 227, common_pid: 2043 } hitcount: 1 | |
2368 | { lat: 228, common_pid: 2039 } hitcount: 7 | |
2369 | { lat: 228, common_pid: 2036 } hitcount: 14 | |
2370 | { lat: 229, common_pid: 2039 } hitcount: 9 | |
2371 | { lat: 229, common_pid: 2036 } hitcount: 8 | |
2372 | { lat: 229, common_pid: 2038 } hitcount: 1 | |
2373 | { lat: 230, common_pid: 2039 } hitcount: 11 | |
2374 | { lat: 230, common_pid: 2036 } hitcount: 6 | |
2375 | { lat: 230, common_pid: 2043 } hitcount: 1 | |
2376 | { lat: 230, common_pid: 2042 } hitcount: 2 | |
2377 | { lat: 231, common_pid: 2041 } hitcount: 1 | |
2378 | { lat: 231, common_pid: 2036 } hitcount: 6 | |
2379 | { lat: 231, common_pid: 2043 } hitcount: 1 | |
2380 | { lat: 231, common_pid: 2039 } hitcount: 8 | |
2381 | { lat: 232, common_pid: 2037 } hitcount: 1 | |
2382 | { lat: 232, common_pid: 2039 } hitcount: 6 | |
2383 | { lat: 232, common_pid: 2040 } hitcount: 2 | |
2384 | { lat: 232, common_pid: 2036 } hitcount: 5 | |
2385 | { lat: 232, common_pid: 2043 } hitcount: 1 | |
2386 | { lat: 233, common_pid: 2036 } hitcount: 5 | |
2387 | { lat: 233, common_pid: 2039 } hitcount: 11 | |
2388 | { lat: 234, common_pid: 2039 } hitcount: 4 | |
2389 | { lat: 234, common_pid: 2038 } hitcount: 2 | |
2390 | { lat: 234, common_pid: 2043 } hitcount: 2 | |
2391 | { lat: 234, common_pid: 2036 } hitcount: 11 | |
2392 | { lat: 234, common_pid: 2040 } hitcount: 1 | |
2393 | { lat: 235, common_pid: 2037 } hitcount: 2 | |
2394 | { lat: 235, common_pid: 2036 } hitcount: 8 | |
2395 | { lat: 235, common_pid: 2043 } hitcount: 2 | |
2396 | { lat: 235, common_pid: 2039 } hitcount: 5 | |
2397 | { lat: 235, common_pid: 2042 } hitcount: 2 | |
2398 | { lat: 235, common_pid: 2040 } hitcount: 4 | |
2399 | { lat: 235, common_pid: 2041 } hitcount: 1 | |
2400 | { lat: 236, common_pid: 2036 } hitcount: 7 | |
2401 | { lat: 236, common_pid: 2037 } hitcount: 1 | |
2402 | { lat: 236, common_pid: 2041 } hitcount: 5 | |
2403 | { lat: 236, common_pid: 2039 } hitcount: 3 | |
2404 | { lat: 236, common_pid: 2043 } hitcount: 9 | |
2405 | { lat: 236, common_pid: 2040 } hitcount: 7 | |
2406 | { lat: 237, common_pid: 2037 } hitcount: 1 | |
2407 | { lat: 237, common_pid: 2040 } hitcount: 1 | |
2408 | { lat: 237, common_pid: 2036 } hitcount: 9 | |
2409 | { lat: 237, common_pid: 2039 } hitcount: 3 | |
2410 | { lat: 237, common_pid: 2043 } hitcount: 8 | |
2411 | { lat: 237, common_pid: 2042 } hitcount: 2 | |
2412 | { lat: 237, common_pid: 2041 } hitcount: 2 | |
2413 | { lat: 238, common_pid: 2043 } hitcount: 10 | |
2414 | { lat: 238, common_pid: 2040 } hitcount: 1 | |
2415 | { lat: 238, common_pid: 2037 } hitcount: 9 | |
2416 | { lat: 238, common_pid: 2038 } hitcount: 1 | |
2417 | { lat: 238, common_pid: 2039 } hitcount: 1 | |
2418 | { lat: 238, common_pid: 2042 } hitcount: 3 | |
2419 | { lat: 238, common_pid: 2036 } hitcount: 7 | |
2420 | { lat: 239, common_pid: 2041 } hitcount: 1 | |
2421 | { lat: 239, common_pid: 2043 } hitcount: 11 | |
2422 | { lat: 239, common_pid: 2037 } hitcount: 11 | |
2423 | { lat: 239, common_pid: 2038 } hitcount: 6 | |
2424 | { lat: 239, common_pid: 2036 } hitcount: 7 | |
2425 | { lat: 239, common_pid: 2040 } hitcount: 1 | |
2426 | { lat: 239, common_pid: 2042 } hitcount: 9 | |
2427 | { lat: 240, common_pid: 2037 } hitcount: 29 | |
2428 | { lat: 240, common_pid: 2043 } hitcount: 15 | |
2429 | { lat: 240, common_pid: 2040 } hitcount: 44 | |
2430 | { lat: 240, common_pid: 2039 } hitcount: 1 | |
2431 | { lat: 240, common_pid: 2041 } hitcount: 2 | |
2432 | { lat: 240, common_pid: 2038 } hitcount: 1 | |
2433 | { lat: 240, common_pid: 2036 } hitcount: 10 | |
2434 | { lat: 240, common_pid: 2042 } hitcount: 13 | |
2435 | { lat: 241, common_pid: 2036 } hitcount: 21 | |
2436 | { lat: 241, common_pid: 2041 } hitcount: 36 | |
2437 | { lat: 241, common_pid: 2037 } hitcount: 34 | |
2438 | { lat: 241, common_pid: 2042 } hitcount: 14 | |
2439 | { lat: 241, common_pid: 2040 } hitcount: 94 | |
2440 | { lat: 241, common_pid: 2039 } hitcount: 12 | |
2441 | { lat: 241, common_pid: 2038 } hitcount: 2 | |
2442 | { lat: 241, common_pid: 2043 } hitcount: 28 | |
2443 | { lat: 242, common_pid: 2040 } hitcount: 109 | |
2444 | { lat: 242, common_pid: 2041 } hitcount: 506 | |
2445 | { lat: 242, common_pid: 2039 } hitcount: 155 | |
2446 | { lat: 242, common_pid: 2042 } hitcount: 21 | |
2447 | { lat: 242, common_pid: 2037 } hitcount: 52 | |
2448 | { lat: 242, common_pid: 2043 } hitcount: 21 | |
2449 | { lat: 242, common_pid: 2036 } hitcount: 16 | |
2450 | { lat: 242, common_pid: 2038 } hitcount: 156 | |
2451 | { lat: 243, common_pid: 2037 } hitcount: 46 | |
2452 | { lat: 243, common_pid: 2039 } hitcount: 40 | |
2453 | { lat: 243, common_pid: 2042 } hitcount: 119 | |
2454 | { lat: 243, common_pid: 2041 } hitcount: 611 | |
2455 | { lat: 243, common_pid: 2036 } hitcount: 69 | |
2456 | { lat: 243, common_pid: 2038 } hitcount: 784 | |
2457 | { lat: 243, common_pid: 2040 } hitcount: 323 | |
2458 | { lat: 243, common_pid: 2043 } hitcount: 14 | |
2459 | { lat: 244, common_pid: 2043 } hitcount: 35 | |
2460 | { lat: 244, common_pid: 2042 } hitcount: 305 | |
2461 | { lat: 244, common_pid: 2039 } hitcount: 8 | |
2462 | { lat: 244, common_pid: 2040 } hitcount: 4515 | |
2463 | { lat: 244, common_pid: 2038 } hitcount: 371 | |
2464 | { lat: 244, common_pid: 2037 } hitcount: 31 | |
2465 | { lat: 244, common_pid: 2036 } hitcount: 114 | |
2466 | { lat: 244, common_pid: 2041 } hitcount: 3396 | |
2467 | { lat: 245, common_pid: 2036 } hitcount: 700 | |
2468 | { lat: 245, common_pid: 2041 } hitcount: 2772 | |
2469 | { lat: 245, common_pid: 2037 } hitcount: 268 | |
2470 | { lat: 245, common_pid: 2039 } hitcount: 472 | |
2471 | { lat: 245, common_pid: 2038 } hitcount: 2758 | |
2472 | { lat: 245, common_pid: 2042 } hitcount: 3833 | |
2473 | { lat: 245, common_pid: 2040 } hitcount: 3105 | |
2474 | { lat: 245, common_pid: 2043 } hitcount: 645 | |
2475 | { lat: 246, common_pid: 2038 } hitcount: 3451 | |
2476 | { lat: 246, common_pid: 2041 } hitcount: 142 | |
2477 | { lat: 246, common_pid: 2037 } hitcount: 5101 | |
2478 | { lat: 246, common_pid: 2040 } hitcount: 68 | |
2479 | { lat: 246, common_pid: 2043 } hitcount: 5099 | |
2480 | { lat: 246, common_pid: 2039 } hitcount: 5608 | |
2481 | { lat: 246, common_pid: 2042 } hitcount: 3723 | |
2482 | { lat: 246, common_pid: 2036 } hitcount: 4738 | |
2483 | { lat: 247, common_pid: 2042 } hitcount: 312 | |
2484 | { lat: 247, common_pid: 2043 } hitcount: 2385 | |
2485 | { lat: 247, common_pid: 2041 } hitcount: 452 | |
2486 | { lat: 247, common_pid: 2038 } hitcount: 792 | |
2487 | { lat: 247, common_pid: 2040 } hitcount: 78 | |
2488 | { lat: 247, common_pid: 2036 } hitcount: 2375 | |
2489 | { lat: 247, common_pid: 2039 } hitcount: 1834 | |
2490 | { lat: 247, common_pid: 2037 } hitcount: 2655 | |
2491 | { lat: 248, common_pid: 2037 } hitcount: 36 | |
2492 | { lat: 248, common_pid: 2042 } hitcount: 11 | |
2493 | { lat: 248, common_pid: 2038 } hitcount: 122 | |
2494 | { lat: 248, common_pid: 2036 } hitcount: 135 | |
2495 | { lat: 248, common_pid: 2039 } hitcount: 26 | |
2496 | { lat: 248, common_pid: 2041 } hitcount: 503 | |
2497 | { lat: 248, common_pid: 2043 } hitcount: 66 | |
2498 | { lat: 248, common_pid: 2040 } hitcount: 46 | |
2499 | { lat: 249, common_pid: 2037 } hitcount: 29 | |
2500 | { lat: 249, common_pid: 2038 } hitcount: 1 | |
2501 | { lat: 249, common_pid: 2043 } hitcount: 29 | |
2502 | { lat: 249, common_pid: 2039 } hitcount: 8 | |
2503 | { lat: 249, common_pid: 2042 } hitcount: 56 | |
2504 | { lat: 249, common_pid: 2040 } hitcount: 27 | |
2505 | { lat: 249, common_pid: 2041 } hitcount: 11 | |
2506 | { lat: 249, common_pid: 2036 } hitcount: 27 | |
2507 | { lat: 250, common_pid: 2038 } hitcount: 1 | |
2508 | { lat: 250, common_pid: 2036 } hitcount: 30 | |
2509 | { lat: 250, common_pid: 2040 } hitcount: 19 | |
2510 | { lat: 250, common_pid: 2043 } hitcount: 22 | |
2511 | { lat: 250, common_pid: 2042 } hitcount: 20 | |
2512 | { lat: 250, common_pid: 2041 } hitcount: 1 | |
2513 | { lat: 250, common_pid: 2039 } hitcount: 6 | |
2514 | { lat: 250, common_pid: 2037 } hitcount: 48 | |
2515 | { lat: 251, common_pid: 2037 } hitcount: 43 | |
2516 | { lat: 251, common_pid: 2039 } hitcount: 1 | |
2517 | { lat: 251, common_pid: 2036 } hitcount: 12 | |
2518 | { lat: 251, common_pid: 2042 } hitcount: 2 | |
2519 | { lat: 251, common_pid: 2041 } hitcount: 1 | |
2520 | { lat: 251, common_pid: 2043 } hitcount: 15 | |
2521 | { lat: 251, common_pid: 2040 } hitcount: 3 | |
2522 | { lat: 252, common_pid: 2040 } hitcount: 1 | |
2523 | { lat: 252, common_pid: 2036 } hitcount: 12 | |
2524 | { lat: 252, common_pid: 2037 } hitcount: 21 | |
2525 | { lat: 252, common_pid: 2043 } hitcount: 14 | |
2526 | { lat: 253, common_pid: 2037 } hitcount: 21 | |
2527 | { lat: 253, common_pid: 2039 } hitcount: 2 | |
2528 | { lat: 253, common_pid: 2036 } hitcount: 9 | |
2529 | { lat: 253, common_pid: 2043 } hitcount: 6 | |
2530 | { lat: 253, common_pid: 2040 } hitcount: 1 | |
2531 | { lat: 254, common_pid: 2036 } hitcount: 8 | |
2532 | { lat: 254, common_pid: 2043 } hitcount: 3 | |
2533 | { lat: 254, common_pid: 2041 } hitcount: 1 | |
2534 | { lat: 254, common_pid: 2042 } hitcount: 1 | |
2535 | { lat: 254, common_pid: 2039 } hitcount: 1 | |
2536 | { lat: 254, common_pid: 2037 } hitcount: 12 | |
2537 | { lat: 255, common_pid: 2043 } hitcount: 1 | |
2538 | { lat: 255, common_pid: 2037 } hitcount: 2 | |
2539 | { lat: 255, common_pid: 2036 } hitcount: 2 | |
2540 | { lat: 255, common_pid: 2039 } hitcount: 8 | |
2541 | { lat: 256, common_pid: 2043 } hitcount: 1 | |
2542 | { lat: 256, common_pid: 2036 } hitcount: 4 | |
2543 | { lat: 256, common_pid: 2039 } hitcount: 6 | |
2544 | { lat: 257, common_pid: 2039 } hitcount: 5 | |
2545 | { lat: 257, common_pid: 2036 } hitcount: 4 | |
2546 | { lat: 258, common_pid: 2039 } hitcount: 5 | |
2547 | { lat: 258, common_pid: 2036 } hitcount: 2 | |
2548 | { lat: 259, common_pid: 2036 } hitcount: 7 | |
2549 | { lat: 259, common_pid: 2039 } hitcount: 7 | |
2550 | { lat: 260, common_pid: 2036 } hitcount: 8 | |
2551 | { lat: 260, common_pid: 2039 } hitcount: 6 | |
2552 | { lat: 261, common_pid: 2036 } hitcount: 5 | |
2553 | { lat: 261, common_pid: 2039 } hitcount: 7 | |
2554 | { lat: 262, common_pid: 2039 } hitcount: 5 | |
2555 | { lat: 262, common_pid: 2036 } hitcount: 5 | |
2556 | { lat: 263, common_pid: 2039 } hitcount: 7 | |
2557 | { lat: 263, common_pid: 2036 } hitcount: 7 | |
2558 | { lat: 264, common_pid: 2039 } hitcount: 9 | |
2559 | { lat: 264, common_pid: 2036 } hitcount: 9 | |
2560 | { lat: 265, common_pid: 2036 } hitcount: 5 | |
2561 | { lat: 265, common_pid: 2039 } hitcount: 1 | |
2562 | { lat: 266, common_pid: 2036 } hitcount: 1 | |
2563 | { lat: 266, common_pid: 2039 } hitcount: 3 | |
2564 | { lat: 267, common_pid: 2036 } hitcount: 1 | |
2565 | { lat: 267, common_pid: 2039 } hitcount: 3 | |
2566 | { lat: 268, common_pid: 2036 } hitcount: 1 | |
2567 | { lat: 268, common_pid: 2039 } hitcount: 6 | |
2568 | { lat: 269, common_pid: 2036 } hitcount: 1 | |
2569 | { lat: 269, common_pid: 2043 } hitcount: 1 | |
2570 | { lat: 269, common_pid: 2039 } hitcount: 2 | |
2571 | { lat: 270, common_pid: 2040 } hitcount: 1 | |
2572 | { lat: 270, common_pid: 2039 } hitcount: 6 | |
2573 | { lat: 271, common_pid: 2041 } hitcount: 1 | |
2574 | { lat: 271, common_pid: 2039 } hitcount: 5 | |
2575 | { lat: 272, common_pid: 2039 } hitcount: 10 | |
2576 | { lat: 273, common_pid: 2039 } hitcount: 8 | |
2577 | { lat: 274, common_pid: 2039 } hitcount: 2 | |
2578 | { lat: 275, common_pid: 2039 } hitcount: 1 | |
2579 | { lat: 276, common_pid: 2039 } hitcount: 2 | |
2580 | { lat: 276, common_pid: 2037 } hitcount: 1 | |
2581 | { lat: 276, common_pid: 2038 } hitcount: 1 | |
2582 | { lat: 277, common_pid: 2039 } hitcount: 1 | |
2583 | { lat: 277, common_pid: 2042 } hitcount: 1 | |
2584 | { lat: 278, common_pid: 2039 } hitcount: 1 | |
2585 | { lat: 279, common_pid: 2039 } hitcount: 4 | |
2586 | { lat: 279, common_pid: 2043 } hitcount: 1 | |
2587 | { lat: 280, common_pid: 2039 } hitcount: 3 | |
2588 | { lat: 283, common_pid: 2036 } hitcount: 2 | |
2589 | { lat: 284, common_pid: 2039 } hitcount: 1 | |
2590 | { lat: 284, common_pid: 2043 } hitcount: 1 | |
2591 | { lat: 288, common_pid: 2039 } hitcount: 1 | |
2592 | { lat: 289, common_pid: 2039 } hitcount: 1 | |
2593 | { lat: 300, common_pid: 2039 } hitcount: 1 | |
2594 | { lat: 384, common_pid: 2039 } hitcount: 1 | |
2595 | ||
2596 | Totals: | |
2597 | Hits: 67625 | |
2598 | Entries: 278 | |
2599 | Dropped: 0 | |
d3439f9d SRV |
2600 | |
2601 | Note, the writes are around the sleep, so ideally they will all be of 250 | |
2602 | microseconds. If you are wondering how there are several that are under | |
2603 | 250 microseconds, that is because the way cyclictest works, is if one | |
2604 | iteration comes in late, the next one will set the timer to wake up less that | |
2605 | 250. That is, if an iteration came in 50 microseconds late, the next wake up | |
2606 | will be at 200 microseconds. | |
2607 | ||
2608 | But this could easily be done in userspace. To make this even more | |
2609 | interesting, we can mix the histogram between events that happened in the | |
ea272257 | 2610 | kernel with trace_marker:: |
d3439f9d SRV |
2611 | |
2612 | # cd /sys/kernel/tracing | |
2613 | # echo 'latency u64 lat' > synthetic_events | |
2614 | # echo 'hist:keys=pid:ts0=common_timestamp.usecs' > events/sched/sched_waking/trigger | |
2615 | # echo 'hist:keys=common_pid:lat=common_timestamp.usecs-$ts0:onmatch(sched.sched_waking).latency($lat) if buf == "end"' > events/ftrace/print/trigger | |
2616 | # echo 'hist:keys=lat,common_pid:sort=lat' > events/synthetic/latency/trigger | |
2617 | ||
2618 | The difference this time is that instead of using the trace_marker to start | |
2619 | the latency, the sched_waking event is used, matching the common_pid for the | |
2620 | trace_marker write with the pid that is being woken by sched_waking. | |
2621 | ||
ea272257 | 2622 | After running cyclictest again with the same parameters, we now have:: |
d3439f9d SRV |
2623 | |
2624 | # cat events/synthetic/latency/hist | |
ea272257 MCC |
2625 | # event histogram |
2626 | # | |
2627 | # trigger info: hist:keys=lat,common_pid:vals=hitcount:sort=lat:size=2048 [active] | |
2628 | # | |
2629 | ||
2630 | { lat: 7, common_pid: 2302 } hitcount: 640 | |
2631 | { lat: 7, common_pid: 2299 } hitcount: 42 | |
2632 | { lat: 7, common_pid: 2303 } hitcount: 18 | |
2633 | { lat: 7, common_pid: 2305 } hitcount: 166 | |
2634 | { lat: 7, common_pid: 2306 } hitcount: 1 | |
2635 | { lat: 7, common_pid: 2301 } hitcount: 91 | |
2636 | { lat: 7, common_pid: 2300 } hitcount: 17 | |
2637 | { lat: 8, common_pid: 2303 } hitcount: 8296 | |
2638 | { lat: 8, common_pid: 2304 } hitcount: 6864 | |
2639 | { lat: 8, common_pid: 2305 } hitcount: 9464 | |
2640 | { lat: 8, common_pid: 2301 } hitcount: 9213 | |
2641 | { lat: 8, common_pid: 2306 } hitcount: 6246 | |
2642 | { lat: 8, common_pid: 2302 } hitcount: 8797 | |
2643 | { lat: 8, common_pid: 2299 } hitcount: 8771 | |
2644 | { lat: 8, common_pid: 2300 } hitcount: 8119 | |
2645 | { lat: 9, common_pid: 2305 } hitcount: 1519 | |
2646 | { lat: 9, common_pid: 2299 } hitcount: 2346 | |
2647 | { lat: 9, common_pid: 2303 } hitcount: 2841 | |
2648 | { lat: 9, common_pid: 2301 } hitcount: 1846 | |
2649 | { lat: 9, common_pid: 2304 } hitcount: 3861 | |
2650 | { lat: 9, common_pid: 2302 } hitcount: 1210 | |
2651 | { lat: 9, common_pid: 2300 } hitcount: 2762 | |
2652 | { lat: 9, common_pid: 2306 } hitcount: 4247 | |
2653 | { lat: 10, common_pid: 2299 } hitcount: 16 | |
2654 | { lat: 10, common_pid: 2306 } hitcount: 333 | |
2655 | { lat: 10, common_pid: 2303 } hitcount: 16 | |
2656 | { lat: 10, common_pid: 2304 } hitcount: 168 | |
2657 | { lat: 10, common_pid: 2302 } hitcount: 240 | |
2658 | { lat: 10, common_pid: 2301 } hitcount: 28 | |
2659 | { lat: 10, common_pid: 2300 } hitcount: 95 | |
2660 | { lat: 10, common_pid: 2305 } hitcount: 18 | |
2661 | { lat: 11, common_pid: 2303 } hitcount: 5 | |
2662 | { lat: 11, common_pid: 2305 } hitcount: 8 | |
2663 | { lat: 11, common_pid: 2306 } hitcount: 221 | |
2664 | { lat: 11, common_pid: 2302 } hitcount: 76 | |
2665 | { lat: 11, common_pid: 2304 } hitcount: 26 | |
2666 | { lat: 11, common_pid: 2300 } hitcount: 125 | |
2667 | { lat: 11, common_pid: 2299 } hitcount: 2 | |
2668 | { lat: 12, common_pid: 2305 } hitcount: 3 | |
2669 | { lat: 12, common_pid: 2300 } hitcount: 6 | |
2670 | { lat: 12, common_pid: 2306 } hitcount: 90 | |
2671 | { lat: 12, common_pid: 2302 } hitcount: 4 | |
2672 | { lat: 12, common_pid: 2303 } hitcount: 1 | |
2673 | { lat: 12, common_pid: 2304 } hitcount: 122 | |
2674 | { lat: 13, common_pid: 2300 } hitcount: 12 | |
2675 | { lat: 13, common_pid: 2301 } hitcount: 1 | |
2676 | { lat: 13, common_pid: 2306 } hitcount: 32 | |
2677 | { lat: 13, common_pid: 2302 } hitcount: 5 | |
2678 | { lat: 13, common_pid: 2305 } hitcount: 1 | |
2679 | { lat: 13, common_pid: 2303 } hitcount: 1 | |
2680 | { lat: 13, common_pid: 2304 } hitcount: 61 | |
2681 | { lat: 14, common_pid: 2303 } hitcount: 4 | |
2682 | { lat: 14, common_pid: 2306 } hitcount: 5 | |
2683 | { lat: 14, common_pid: 2305 } hitcount: 4 | |
2684 | { lat: 14, common_pid: 2304 } hitcount: 62 | |
2685 | { lat: 14, common_pid: 2302 } hitcount: 19 | |
2686 | { lat: 14, common_pid: 2300 } hitcount: 33 | |
2687 | { lat: 14, common_pid: 2299 } hitcount: 1 | |
2688 | { lat: 14, common_pid: 2301 } hitcount: 4 | |
2689 | { lat: 15, common_pid: 2305 } hitcount: 1 | |
2690 | { lat: 15, common_pid: 2302 } hitcount: 25 | |
2691 | { lat: 15, common_pid: 2300 } hitcount: 11 | |
2692 | { lat: 15, common_pid: 2299 } hitcount: 5 | |
2693 | { lat: 15, common_pid: 2301 } hitcount: 1 | |
2694 | { lat: 15, common_pid: 2304 } hitcount: 8 | |
2695 | { lat: 15, common_pid: 2303 } hitcount: 1 | |
2696 | { lat: 15, common_pid: 2306 } hitcount: 6 | |
2697 | { lat: 16, common_pid: 2302 } hitcount: 31 | |
2698 | { lat: 16, common_pid: 2306 } hitcount: 3 | |
2699 | { lat: 16, common_pid: 2300 } hitcount: 5 | |
2700 | { lat: 17, common_pid: 2302 } hitcount: 6 | |
2701 | { lat: 17, common_pid: 2303 } hitcount: 1 | |
2702 | { lat: 18, common_pid: 2304 } hitcount: 1 | |
2703 | { lat: 18, common_pid: 2302 } hitcount: 8 | |
2704 | { lat: 18, common_pid: 2299 } hitcount: 1 | |
2705 | { lat: 18, common_pid: 2301 } hitcount: 1 | |
2706 | { lat: 19, common_pid: 2303 } hitcount: 4 | |
2707 | { lat: 19, common_pid: 2304 } hitcount: 5 | |
2708 | { lat: 19, common_pid: 2302 } hitcount: 4 | |
2709 | { lat: 19, common_pid: 2299 } hitcount: 3 | |
2710 | { lat: 19, common_pid: 2306 } hitcount: 1 | |
2711 | { lat: 19, common_pid: 2300 } hitcount: 4 | |
2712 | { lat: 19, common_pid: 2305 } hitcount: 5 | |
2713 | { lat: 20, common_pid: 2299 } hitcount: 2 | |
2714 | { lat: 20, common_pid: 2302 } hitcount: 3 | |
2715 | { lat: 20, common_pid: 2305 } hitcount: 1 | |
2716 | { lat: 20, common_pid: 2300 } hitcount: 2 | |
2717 | { lat: 20, common_pid: 2301 } hitcount: 2 | |
2718 | { lat: 20, common_pid: 2303 } hitcount: 3 | |
2719 | { lat: 21, common_pid: 2305 } hitcount: 1 | |
2720 | { lat: 21, common_pid: 2299 } hitcount: 5 | |
2721 | { lat: 21, common_pid: 2303 } hitcount: 4 | |
2722 | { lat: 21, common_pid: 2302 } hitcount: 7 | |
2723 | { lat: 21, common_pid: 2300 } hitcount: 1 | |
2724 | { lat: 21, common_pid: 2301 } hitcount: 5 | |
2725 | { lat: 21, common_pid: 2304 } hitcount: 2 | |
2726 | { lat: 22, common_pid: 2302 } hitcount: 5 | |
2727 | { lat: 22, common_pid: 2303 } hitcount: 1 | |
2728 | { lat: 22, common_pid: 2306 } hitcount: 3 | |
2729 | { lat: 22, common_pid: 2301 } hitcount: 2 | |
2730 | { lat: 22, common_pid: 2300 } hitcount: 1 | |
2731 | { lat: 22, common_pid: 2299 } hitcount: 1 | |
2732 | { lat: 22, common_pid: 2305 } hitcount: 1 | |
2733 | { lat: 22, common_pid: 2304 } hitcount: 1 | |
2734 | { lat: 23, common_pid: 2299 } hitcount: 1 | |
2735 | { lat: 23, common_pid: 2306 } hitcount: 2 | |
2736 | { lat: 23, common_pid: 2302 } hitcount: 6 | |
2737 | { lat: 24, common_pid: 2302 } hitcount: 3 | |
2738 | { lat: 24, common_pid: 2300 } hitcount: 1 | |
2739 | { lat: 24, common_pid: 2306 } hitcount: 2 | |
2740 | { lat: 24, common_pid: 2305 } hitcount: 1 | |
2741 | { lat: 24, common_pid: 2299 } hitcount: 1 | |
2742 | { lat: 25, common_pid: 2300 } hitcount: 1 | |
2743 | { lat: 25, common_pid: 2302 } hitcount: 4 | |
2744 | { lat: 26, common_pid: 2302 } hitcount: 2 | |
2745 | { lat: 27, common_pid: 2305 } hitcount: 1 | |
2746 | { lat: 27, common_pid: 2300 } hitcount: 1 | |
2747 | { lat: 27, common_pid: 2302 } hitcount: 3 | |
2748 | { lat: 28, common_pid: 2306 } hitcount: 1 | |
2749 | { lat: 28, common_pid: 2302 } hitcount: 4 | |
2750 | { lat: 29, common_pid: 2302 } hitcount: 1 | |
2751 | { lat: 29, common_pid: 2300 } hitcount: 2 | |
2752 | { lat: 29, common_pid: 2306 } hitcount: 1 | |
2753 | { lat: 29, common_pid: 2304 } hitcount: 1 | |
2754 | { lat: 30, common_pid: 2302 } hitcount: 4 | |
2755 | { lat: 31, common_pid: 2302 } hitcount: 6 | |
2756 | { lat: 32, common_pid: 2302 } hitcount: 1 | |
2757 | { lat: 33, common_pid: 2299 } hitcount: 1 | |
2758 | { lat: 33, common_pid: 2302 } hitcount: 3 | |
2759 | { lat: 34, common_pid: 2302 } hitcount: 2 | |
2760 | { lat: 35, common_pid: 2302 } hitcount: 1 | |
2761 | { lat: 35, common_pid: 2304 } hitcount: 1 | |
2762 | { lat: 36, common_pid: 2302 } hitcount: 4 | |
2763 | { lat: 37, common_pid: 2302 } hitcount: 6 | |
2764 | { lat: 38, common_pid: 2302 } hitcount: 2 | |
2765 | { lat: 39, common_pid: 2302 } hitcount: 2 | |
2766 | { lat: 39, common_pid: 2304 } hitcount: 1 | |
2767 | { lat: 40, common_pid: 2304 } hitcount: 2 | |
2768 | { lat: 40, common_pid: 2302 } hitcount: 5 | |
2769 | { lat: 41, common_pid: 2304 } hitcount: 1 | |
2770 | { lat: 41, common_pid: 2302 } hitcount: 8 | |
2771 | { lat: 42, common_pid: 2302 } hitcount: 6 | |
2772 | { lat: 42, common_pid: 2304 } hitcount: 1 | |
2773 | { lat: 43, common_pid: 2302 } hitcount: 3 | |
2774 | { lat: 43, common_pid: 2304 } hitcount: 4 | |
2775 | { lat: 44, common_pid: 2302 } hitcount: 6 | |
2776 | { lat: 45, common_pid: 2302 } hitcount: 5 | |
2777 | { lat: 46, common_pid: 2302 } hitcount: 5 | |
2778 | { lat: 47, common_pid: 2302 } hitcount: 7 | |
2779 | { lat: 48, common_pid: 2301 } hitcount: 1 | |
2780 | { lat: 48, common_pid: 2302 } hitcount: 9 | |
2781 | { lat: 49, common_pid: 2302 } hitcount: 3 | |
2782 | { lat: 50, common_pid: 2302 } hitcount: 1 | |
2783 | { lat: 50, common_pid: 2301 } hitcount: 1 | |
2784 | { lat: 51, common_pid: 2302 } hitcount: 2 | |
2785 | { lat: 51, common_pid: 2301 } hitcount: 1 | |
2786 | { lat: 61, common_pid: 2302 } hitcount: 1 | |
2787 | { lat: 110, common_pid: 2302 } hitcount: 1 | |
2788 | ||
2789 | Totals: | |
2790 | Hits: 89565 | |
2791 | Entries: 158 | |
2792 | Dropped: 0 | |
d3439f9d SRV |
2793 | |
2794 | This doesn't tell us any information about how late cyclictest may have | |
2795 | woken up, but it does show us a nice histogram of how long it took from | |
2796 | the time that cyclictest was woken to the time it made it into user space. |