1 .TH BTT 1 "September 29, 2007" "blktrace git\-20070910192508" ""
5 btt \- analyse block i/o traces produces by blktrace
10 [ \-a | \-\-seek\-absolute ]
12 [ \-A | \-\-all\-data ]
14 [ \-B <\fIoutput name\fR> | \-\-dump\-blocknos=<\fIoutput name\fR> ]
16 [ \-d <\fIseconds\fR> | \-\-range\-delta=<\fIseconds\fR> ]
18 [ \-D <\fIdev;...\fR> | \-\-devices=<\fIdev;...\fR> ]
20 [ \-e <\fIexe,...\fR> | \-\-exes=<\fIexe,...\fR> ]
24 [ \-i <\fIinput name\fR> | \-\-input\-file=<\fIinput name\fR> ]
26 [ \-I <\fIoutput name\fR> | \-\-iostat=<\fIoutput name\fR> ]
28 [ \-l <\fIoutput name\fR> | \-\-d2c\-latencies=<\fIoutput name\fR> ]
30 [ \-L <\fIfreq\fR> | \-\-periodic\-latencies=<\fIfreq\fR> ]
32 [ \-M <\fIdev map\fR> | \-\-dev\-maps=<\fIdev map\fR>
34 [ \-o <\fIoutput name\fR> | \-\-output\-file=<\fIoutput name\fR> ]
36 [ \-p <\fIoutput name\fR> | \-\-per\-io\-dump=<\fIoutput name\fR> ]
38 [ \-P <\fIoutput name\fR> | \-\-per\-io\-trees=<\fIoutput name\fR> ]
40 [ \-q <\fIoutput name\fR> | \-\-q2c\-latencies=<\fIoutput name\fR> ]
42 [ \-Q <\fIoutput name\fR> | \-\-active\-queue\-depth=<\fIoutput name\fR> ]
44 [ \-s <\fIoutput name\fR> | \-\-seeks=<\fIoutput name\fR> ]
46 [ \-S <\fIinterval\fR> | \-\-iostat\-interval=<\fIinterval\fR> ]
48 [ \-t <\fIsec\fR> | \-\-time\-start=<\fIsec\fR> ]
50 [ \-T <\fIsec\fR> | \-\-time\-end=<\fIsec\fR> ]
52 [ \-u <\fIoutput name\fR> | \-\-unplug\-hist=<\fIoutput name\fR> ]
58 [ \-z <\fIoutput name\fR> | \-\-q2d\-latencies=<\fIoutput name\fR> ]
63 btt is a post\-processing tool for the block layer IO tracing tool called
64 blktrace(8). As noted in its documentation, blktrace
65 is a block layer IO tracing mechanism which provides detailed
66 information about request queue operations up to user space.
68 btt will take in binary dump data from blkparse, and analyse the events,
69 producing a series of output from the analysis. It will also build .dat
70 files containing "range data" \-\- showing things like Q activity (periods
71 of time while Q events are being produced), C activity (likewise for
72 command completions), and etc.
74 Included with the distribution is a simple 3D plotting utility,
75 \fIbno_plot\fR, which can plot the block numbers btss outputs if the \fI-B\fR
76 option is specified. The display will display each IO generated, with the time
77 (seconds) along the X-axis, the block number (start) along the Y-axis and the
78 number of blocks transferred in the IO represented along the Z-axis.
87 When specified on the command line, this directs btt to calculate
88 seek distances based solely upon the ending block address of one IO,
89 and the start of the next. By default \fBbtt\fR uses the concept
90 of the closeness to either the beginning or end of the previous IO. See
91 the Users Manual for more details about seek distances.
98 Normally \fBbtt\fR will not print out verbose information concerning
99 per-process and per-device data. If you desire that level of detail you can
103 .B \-B <\fIoutput name\fR>
105 .B \-\-dump\-blocknos=<\fIoutput name\fR>
107 This option will output absolute block numbers to three files prefixed
108 by the specified output name:
110 .I prefix_device_r.dat
112 All read block numbers are output, first column is time (seconds), second is
113 the block number, and the third column is the ending block number.
115 .I prefix_device_w.dat
117 All write block numbers are output, first column is time (seconds), second is
118 the block number, and the third column is the ending block number.
120 .I prefix_device_c.dat
122 All block numbers (read and write) are output, first column is time (seconds),
123 second is the block number, and the third column is the ending block number.
126 .B \-d <\fIseconds\fR>
128 .B \-\-range\-delta=<\fIseconds\fR>
130 \fBbtt\fR outputs a file containing Q and C activity, the notion of active
131 traces simply means that there are Q or C traces occurring within a certain
132 period of each other. The default values is 0.1 seconds; with this option
133 allowing one to change that granularity. The smaller the value, the more data
137 .B \-D <\fIdev;...\fR>
139 .B \-\-devices=<\fIdev;...\fR>
141 Normally, \fBbtt\fR will produce data for all devices detected in the
142 traces parsed. With this option, one can reduce the analysis to one or more
143 devices provided in the string passed to this option. The device identifiers
144 are the major and minor number of each device, and each device identifier is
145 separated by a colon (:). A valid specifier for devices 8,0 and 8,8 would then
149 .B \-e <\fIexe,...\fR>
151 .B \-\-exes=<\fIexe,...\fR>
153 The \-e option supplies the list of executables that will have I/Os
161 Shows a short summary of possible command line option
164 .B \-i <\fIinput name\fR>
166 .B \-\-input\-file <\fIinput file\fR>
168 Specifies the input file to analyse. This should be a trace file produced
169 by \fIblktrace\fR (8).
172 .B \-I <\fIoutput name\fR>
174 .B \-\-iostat=<\fIoutput name\fR>
176 The \-I option directs btt to output iostat\-like data to the specified
177 file. Refer to the iostat (sysstat) documentation for details on the
181 .B \-l <\fIoutput name\fR>
183 .B \-\-d2c\-latencies=<\fIoutput name\fR>
185 The \-l option allows one to output per\-IO D2C latencies
186 respectively. The supplied argument provides the basis for the output
187 name for each device.
192 .B \-\-periodic\-latencies=<\fIfreq\fR>
194 The \-L option allows one to output periodic latency information for both
195 Q2C and D2C latencies. The frequency specified will regulate how often
196 an average latency is output -- a floating point value expressing seconds.
199 .B \-M <\fIdev map\fR>
201 .B \-\-dev\-maps=<\fIdev map\fR>
203 The \-M option takes in a file generated by the provided script
204 (gen_disk_info.py), and allows for better output of device names.
207 .B \-o <\fIoutput name\fR>
209 .B \-\-output\-file=<\fIoutput name\fR>
211 Specifies the output file name.
214 .B \-p <\fIoutput name\fR>
216 .B \-\-per\-io\-dump=<\fIoutput name\fR>
218 The \-p option will generate a file that contains a list of all IO
219 "sequences" \- showing the parts of each IO (Q, A, I/M, D, & C).
222 .B \-P <\fIoutput name\fR>
224 .B \-\-per\-io\-trees=<\fIoutput name\fR>
226 The \-P option will generate a file that contains a list of all IO
227 "sequences" \- showing only the Q, D & C operation times. The D & C
228 time values are separated from the Q time values with a vertical bar.
231 .B \-q <\fIoutput name\fR>
233 .B \-\-q2c\-latencies=<\fIoutput name\fR>
235 The \-q option allows one to output per\-IO Q2C latencies
236 respectively. The supplied argument provides the basis for the output
237 name for each device.
240 .B \-Q <\fIoutput name\fR>
242 .B \-\-active\-queue\-depth=<\fIoutput name\fR>
244 The \-Q option allows one to output data files showing the time stamp
245 and the depth of active commands (those issued but not completed).
248 .B \-s <\fIoutput name\fR>
250 .B \-\-seeks=<\fIoutput name\fR>
252 The \-s option instructs btt to output seek data, the argument provided
253 is the basis for file names output. There are two files per device,
254 read seeks and write seeks.
257 .B \-S <\fIinterval\fR>
259 .B \-\-iostat\-interval=<\fIinterval\fR>
261 The \-S option specifies the interval to use between data
262 output, it defaults to once per second.
267 .B \-\-time\-start=<\fIsec\fR>
271 .B \-\-time\-end=<\fIsec\fR>
273 The \-t/\-T options allow one to set a start and/or end time for analysing
274 \- analysing will only be done for traces after \-t's argument and before
275 \-T's argument. (\-t and \-T are optional, so if you specify just \-t,
276 analysis will occur for all traces after the time specified. Similarly,
277 if only \-T is specified, analysis stops after \-T's seconds.)
280 .B \-u <\fIoutput name\fR>
282 .B \-\-unplug\-hist=<\fIoutput name\fR>
284 This option instructs \fBbtt\fR to generate a data file containing histogram
285 information for unplug traces on a per device basis. It shows how many
286 times an unplug was hit with a specified number of IOs released. There are 21
287 output values into the file, as follows:
290 a value of 0 represents 0..4 counts
292 a value of 1 represents 5..9 counts
294 a value of 2 represents 10..14 counts
298 a value of 20 represents 100+ counts
302 The file name(s) generated use the text string passed as an argument for
303 the prefix, followed by the device identifier in \fImajor,minor\fR
304 form, with a \fI.dat\fR extension. For example, with \fI\-u
305 up_hist\fR specified on the command line: \fIup_hist_008,032.dat\fR.
312 Shows the version of btt.
319 Requests a more verbose output.
322 .B \-z <\fIoutput name\fR>
324 .B \-\-q2d\-latencies=<\fIoutput name\fR>
326 The \-z option allows one to output per\-IO Q2D latencies
327 respectively. The supplied argument provides the basis for the output
328 name for each device.
333 \fIbtt\fR was written by Alan D. Brunelle. This man page was created
334 from the \fIblktrace\fR documentation by Bas Zoetekouw.
338 Report bugs to <linux\-btrace@vger.kernel.org>
341 Copyright \(co 2006 Jens Axboe, Alan D. Brunelle and Nathan Scott.
343 This is free software. You may redistribute copies of it under the terms of
344 the GNU General Public License <http://www.gnu.org/licenses/gpl.html>.
345 There is NO WARRANTY, to the extent permitted by law.
347 This manual page was created for Debian by Bas Zoetekouw. It was derived from
348 the documentation provided by the authors and it may be used, distributed and
349 modified under the terms of the GNU General Public License, version 2.
351 On Debian systems, the text of the GNU General Public License can be found in
352 /usr/share/common\-licenses/GPL\-2.
355 The btt Users Guide, which can be found in /usr/share/doc/blktrace/btt.pdf
357 bno_plot (1), blktrace (8), blkparse (1), verify_blkparse (1), blkrawverify (1), btt (1)