Commit | Line | Data |
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86a9eee0 | 1 | perf-diff(1) |
4778e0e8 | 2 | ============ |
86a9eee0 ACM |
3 | |
4 | NAME | |
5 | ---- | |
3a3beae8 | 6 | perf-diff - Read perf.data files and display the differential profile |
86a9eee0 ACM |
7 | |
8 | SYNOPSIS | |
9 | -------- | |
10 | [verse] | |
3a3beae8 | 11 | 'perf diff' [baseline file] [data file1] [[data file2] ... ] |
86a9eee0 ACM |
12 | |
13 | DESCRIPTION | |
14 | ----------- | |
3a3beae8 JO |
15 | This command displays the performance difference amongst two or more perf.data |
16 | files captured via perf record. | |
86a9eee0 ACM |
17 | |
18 | If no parameters are passed it will assume perf.data.old and perf.data. | |
19 | ||
863e451f JO |
20 | The differential profile is displayed only for events matching both |
21 | specified perf.data files. | |
22 | ||
94ba462d KL |
23 | If no parameters are passed the samples will be sorted by dso and symbol. |
24 | As the perf.data files could come from different binaries, the symbols addresses | |
25 | could vary. So perf diff is based on the comparison of the files and | |
26 | symbols name. | |
27 | ||
86a9eee0 ACM |
28 | OPTIONS |
29 | ------- | |
5ea4f857 SB |
30 | -D:: |
31 | --dump-raw-trace:: | |
32 | Dump raw trace in ASCII. | |
33 | ||
6b1f3423 DA |
34 | --kallsyms=<file>:: |
35 | kallsyms pathname | |
36 | ||
5ea4f857 SB |
37 | -m:: |
38 | --modules:: | |
39 | Load module symbols. WARNING: use only with -k and LIVE kernel | |
40 | ||
c351c281 ACM |
41 | -d:: |
42 | --dsos=:: | |
43 | Only consider symbols in these dsos. CSV that understands | |
8810f6ce NK |
44 | file://filename entries. This option will affect the percentage |
45 | of the Baseline/Delta column. See --percentage for more info. | |
c351c281 ACM |
46 | |
47 | -C:: | |
48 | --comms=:: | |
49 | Only consider symbols in these comms. CSV that understands | |
8810f6ce NK |
50 | file://filename entries. This option will affect the percentage |
51 | of the Baseline/Delta column. See --percentage for more info. | |
c351c281 ACM |
52 | |
53 | -S:: | |
54 | --symbols=:: | |
55 | Only consider these symbols. CSV that understands | |
8810f6ce NK |
56 | file://filename entries. This option will affect the percentage |
57 | of the Baseline/Delta column. See --percentage for more info. | |
c351c281 ACM |
58 | |
59 | -s:: | |
60 | --sort=:: | |
a2ce067e NK |
61 | Sort by key(s): pid, comm, dso, symbol, cpu, parent, srcline. |
62 | Please see description of --sort in the perf-report man page. | |
c351c281 ACM |
63 | |
64 | -t:: | |
65 | --field-separator=:: | |
66 | ||
67 | Use a special separator character and don't pad with spaces, replacing | |
5ea4f857 | 68 | all occurrences of this separator in symbol names (and other output) |
c351c281 ACM |
69 | with a '.' character, that thus it's the only non valid separator. |
70 | ||
86a9eee0 ACM |
71 | -v:: |
72 | --verbose:: | |
d30531c6 | 73 | Be verbose, for instance, show the raw counts in addition to the |
86a9eee0 | 74 | diff. |
cdccc690 | 75 | |
63b42fce NK |
76 | -q:: |
77 | --quiet:: | |
a527c2c1 | 78 | Do not show any warnings or messages. (Suppress -v) |
63b42fce | 79 | |
5ea4f857 SB |
80 | -f:: |
81 | --force:: | |
e0be62cc | 82 | Don't do ownership validation. |
5ea4f857 | 83 | |
ec5761ea DA |
84 | --symfs=<directory>:: |
85 | Look for files with symbols relative to this directory. | |
5ea4f857 | 86 | |
a06d143e JO |
87 | -b:: |
88 | --baseline-only:: | |
89 | Show only items with match in baseline. | |
90 | ||
7aaf6b35 JO |
91 | -c:: |
92 | --compute:: | |
c8f7bc1a JY |
93 | Differential computation selection - delta, ratio, wdiff, cycles, |
94 | delta-abs (default is delta-abs). Default can be changed using | |
95 | diff.compute config option. See COMPARISON METHODS section for | |
96 | more info. | |
7aaf6b35 | 97 | |
cebf7d51 JY |
98 | --cycles-hist:: |
99 | Report a histogram and the standard deviation for cycles data. | |
100 | It can help us to judge if the reported cycles data is noisy or | |
101 | not. This option should be used with '-c cycles'. | |
102 | ||
61949b21 JO |
103 | -p:: |
104 | --period:: | |
105 | Show period values for both compared hist entries. | |
106 | ||
ed279da2 JO |
107 | -F:: |
108 | --formula:: | |
109 | Show formula for given computation. | |
110 | ||
5f3f8d3b JO |
111 | -o:: |
112 | --order:: | |
d49dd15d | 113 | Specify compute sorting column number. 0 means sorting by baseline |
be57b3fd | 114 | overhead and 1 (default) means sorting by computed value of column 1 |
d49dd15d NK |
115 | (data from the first file other base baseline). Values more than 1 |
116 | can be used only if enough data files are provided. | |
117 | The default value can be set using the diff.order config option. | |
5f3f8d3b | 118 | |
8810f6ce NK |
119 | --percentage:: |
120 | Determine how to display the overhead percentage of filtered entries. | |
121 | Filters can be applied by --comms, --dsos and/or --symbols options. | |
122 | ||
123 | "relative" means it's relative to filtered entries only so that the | |
124 | sum of shown entries will be always 100%. "absolute" means it retains | |
125 | the original value before and after the filter is applied. | |
126 | ||
4802138d JY |
127 | --time:: |
128 | Analyze samples within given time window. It supports time | |
129 | percent with multiple time ranges. Time string is 'a%/n,b%/m,...' | |
130 | or 'a%-b%,c%-%d,...'. | |
131 | ||
132 | For example: | |
133 | ||
134 | Select the second 10% time slice to diff: | |
135 | ||
136 | perf diff --time 10%/2 | |
137 | ||
138 | Select from 0% to 10% time slice to diff: | |
139 | ||
140 | perf diff --time 0%-10% | |
141 | ||
142 | Select the first and the second 10% time slices to diff: | |
143 | ||
144 | perf diff --time 10%/1,10%/2 | |
145 | ||
146 | Select from 0% to 10% and 30% to 40% slices to diff: | |
147 | ||
148 | perf diff --time 0%-10%,30%-40% | |
149 | ||
150 | It also supports analyzing samples within a given time window | |
0ccc69ba AH |
151 | <start>,<stop>. Times have the format seconds.nanoseconds. If 'start' |
152 | is not given (i.e. time string is ',x.y') then analysis starts at | |
153 | the beginning of the file. If stop time is not given (i.e. time | |
a77a05e2 AH |
154 | string is 'x.y,') then analysis goes to the end of the file. |
155 | Multiple ranges can be separated by spaces, which requires the argument | |
156 | to be quoted e.g. --time "1234.567,1234.789 1235," | |
157 | Time string is'a1.b1,c1.d1:a2.b2,c2.d2'. Use ':' to separate timestamps | |
158 | for different perf.data files. | |
4802138d JY |
159 | |
160 | For example, we get the timestamp information from 'perf script'. | |
161 | ||
162 | perf script -i perf.data.old | |
163 | mgen 13940 [000] 3946.361400: ... | |
164 | ||
165 | perf script -i perf.data | |
166 | mgen 13940 [000] 3971.150589 ... | |
167 | ||
168 | perf diff --time 3946.361400,:3971.150589, | |
169 | ||
170 | It analyzes the perf.data.old from the timestamp 3946.361400 to | |
171 | the end of perf.data.old and analyzes the perf.data from the | |
172 | timestamp 3971.150589 to the end of perf.data. | |
173 | ||
daca23b2 JY |
174 | --cpu:: Only diff samples for the list of CPUs provided. Multiple CPUs can |
175 | be provided as a comma-separated list with no space: 0,1. Ranges of | |
176 | CPUs are specified with -: 0-2. Default is to report samples on all | |
177 | CPUs. | |
178 | ||
c1d3e633 JY |
179 | --pid=:: |
180 | Only diff samples for given process ID (comma separated list). | |
181 | ||
182 | --tid=:: | |
183 | Only diff samples for given thread ID (comma separated list). | |
184 | ||
2a09a84c JY |
185 | --stream:: |
186 | Enable hot streams comparison. Stream can be a callchain which is | |
187 | aggregated by the branch records from samples. | |
188 | ||
3a3beae8 JO |
189 | COMPARISON |
190 | ---------- | |
191 | The comparison is governed by the baseline file. The baseline perf.data | |
192 | file is iterated for samples. All other perf.data files specified on | |
193 | the command line are searched for the baseline sample pair. If the pair | |
194 | is found, specified computation is made and result is displayed. | |
195 | ||
196 | All samples from non-baseline perf.data files, that do not match any | |
197 | baseline entry, are displayed with empty space within baseline column | |
198 | and possible computation results (delta) in their related column. | |
199 | ||
200 | Example files samples: | |
201 | - file A with samples f1, f2, f3, f4, f6 | |
202 | - file B with samples f2, f4, f5 | |
203 | - file C with samples f1, f2, f5 | |
204 | ||
205 | Example output: | |
206 | x - computation takes place for pair | |
207 | b - baseline sample percentage | |
208 | ||
209 | - perf diff A B C | |
210 | ||
211 | baseline/A compute/B compute/C samples | |
212 | --------------------------------------- | |
213 | b x f1 | |
214 | b x x f2 | |
215 | b f3 | |
216 | b x f4 | |
217 | b f6 | |
218 | x x f5 | |
219 | ||
220 | - perf diff B A C | |
221 | ||
222 | baseline/B compute/A compute/C samples | |
223 | --------------------------------------- | |
224 | b x x f2 | |
225 | b x f4 | |
226 | b x f5 | |
227 | x x f1 | |
228 | x f3 | |
229 | x f6 | |
230 | ||
231 | - perf diff C B A | |
232 | ||
233 | baseline/C compute/B compute/A samples | |
234 | --------------------------------------- | |
235 | b x f1 | |
236 | b x x f2 | |
237 | b x f5 | |
238 | x f3 | |
239 | x x f4 | |
240 | x f6 | |
241 | ||
7aaf6b35 JO |
242 | COMPARISON METHODS |
243 | ------------------ | |
244 | delta | |
245 | ~~~~~ | |
246 | If specified the 'Delta' column is displayed with value 'd' computed as: | |
247 | ||
248 | d = A->period_percent - B->period_percent | |
249 | ||
250 | with: | |
3a3beae8 | 251 | - A/B being matching hist entry from data/baseline file specified |
7aaf6b35 JO |
252 | (or perf.data/perf.data.old) respectively. |
253 | ||
254 | - period_percent being the % of the hist entry period value within | |
255 | single data file | |
256 | ||
8810f6ce NK |
257 | - with filtering by -C, -d and/or -S, period_percent might be changed |
258 | relative to how entries are filtered. Use --percentage=absolute to | |
259 | prevent such fluctuation. | |
260 | ||
a1668c25 NK |
261 | delta-abs |
262 | ~~~~~~~~~ | |
263 | Same as 'delta` method, but sort the result with the absolute values. | |
264 | ||
7aaf6b35 JO |
265 | ratio |
266 | ~~~~~ | |
267 | If specified the 'Ratio' column is displayed with value 'r' computed as: | |
268 | ||
269 | r = A->period / B->period | |
270 | ||
271 | with: | |
3a3beae8 | 272 | - A/B being matching hist entry from data/baseline file specified |
7aaf6b35 JO |
273 | (or perf.data/perf.data.old) respectively. |
274 | ||
275 | - period being the hist entry period value | |
276 | ||
3a3beae8 JO |
277 | wdiff:WEIGHT-B,WEIGHT-A |
278 | ~~~~~~~~~~~~~~~~~~~~~~~ | |
81d5f958 JO |
279 | If specified the 'Weighted diff' column is displayed with value 'd' computed as: |
280 | ||
281 | d = B->period * WEIGHT-A - A->period * WEIGHT-B | |
282 | ||
3a3beae8 | 283 | - A/B being matching hist entry from data/baseline file specified |
81d5f958 JO |
284 | (or perf.data/perf.data.old) respectively. |
285 | ||
286 | - period being the hist entry period value | |
287 | ||
96355f2c | 288 | - WEIGHT-A/WEIGHT-B being user supplied weights in the the '-c' option |
81d5f958 | 289 | behind ':' separator like '-c wdiff:1,2'. |
96355f2c MI |
290 | - WEIGHT-A being the weight of the data file |
291 | - WEIGHT-B being the weight of the baseline data file | |
7aaf6b35 | 292 | |
c8f7bc1a JY |
293 | cycles |
294 | ~~~~~~ | |
295 | If specified the '[Program Block Range] Cycles Diff' column is displayed. | |
296 | It displays the cycles difference of same program basic block amongst | |
297 | two perf.data. The program basic block is the code between two branches. | |
298 | ||
299 | '[Program Block Range]' indicates the range of a program basic block. | |
300 | Source line is reported if it can be found otherwise uses symbol+offset | |
301 | instead. | |
302 | ||
86a9eee0 ACM |
303 | SEE ALSO |
304 | -------- | |
a2ce067e | 305 | linkperf:perf-record[1], linkperf:perf-report[1] |