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Diffstat (limited to 'tools/perf/Documentation/perf-diff.txt')
| -rw-r--r-- | tools/perf/Documentation/perf-diff.txt | 158 |
1 files changed, 145 insertions, 13 deletions
diff --git a/tools/perf/Documentation/perf-diff.txt b/tools/perf/Documentation/perf-diff.txt index 74d7481ed7a..b3b8abae62b 100644 --- a/tools/perf/Documentation/perf-diff.txt +++ b/tools/perf/Documentation/perf-diff.txt @@ -3,26 +3,25 @@ perf-diff(1) NAME ---- -perf-diff - Read two perf.data files and display the differential profile +perf-diff - Read perf.data files and display the differential profile SYNOPSIS -------- [verse] -'perf diff' [oldfile] [newfile] +'perf diff' [baseline file] [data file1] [[data file2] ... ] DESCRIPTION ----------- -This command displays the performance difference amongst two perf.data files -captured via perf record. +This command displays the performance difference amongst two or more perf.data +files captured via perf record. If no parameters are passed it will assume perf.data.old and perf.data. +The differential profile is displayed only for events matching both +specified perf.data files. + OPTIONS ------- --M:: ---displacement:: - Show position displacement relative to baseline. - -D:: --dump-raw-trace:: Dump raw trace in ASCII. @@ -34,21 +33,25 @@ OPTIONS -d:: --dsos=:: Only consider symbols in these dsos. CSV that understands - file://filename entries. + file://filename entries. This option will affect the percentage + of the Baseline/Delta column. See --percentage for more info. -C:: --comms=:: Only consider symbols in these comms. CSV that understands - file://filename entries. + file://filename entries. This option will affect the percentage + of the Baseline/Delta column. See --percentage for more info. -S:: --symbols=:: Only consider these symbols. CSV that understands - file://filename entries. + file://filename entries. This option will affect the percentage + of the Baseline/Delta column. See --percentage for more info. -s:: --sort=:: - Sort by key(s): pid, comm, dso, symbol. + Sort by key(s): pid, comm, dso, symbol, cpu, parent, srcline. + Please see description of --sort in the perf-report man page. -t:: --field-separator=:: @@ -69,6 +72,135 @@ OPTIONS --symfs=<directory>:: Look for files with symbols relative to this directory. +-b:: +--baseline-only:: + Show only items with match in baseline. + +-c:: +--compute:: + Differential computation selection - delta,ratio,wdiff (default is delta). + See COMPARISON METHODS section for more info. + +-p:: +--period:: + Show period values for both compared hist entries. + +-F:: +--formula:: + Show formula for given computation. + +-o:: +--order:: + Specify compute sorting column number. + +--percentage:: + Determine how to display the overhead percentage of filtered entries. + Filters can be applied by --comms, --dsos and/or --symbols options. + + "relative" means it's relative to filtered entries only so that the + sum of shown entries will be always 100%. "absolute" means it retains + the original value before and after the filter is applied. + +COMPARISON +---------- +The comparison is governed by the baseline file. The baseline perf.data +file is iterated for samples. All other perf.data files specified on +the command line are searched for the baseline sample pair. If the pair +is found, specified computation is made and result is displayed. + +All samples from non-baseline perf.data files, that do not match any +baseline entry, are displayed with empty space within baseline column +and possible computation results (delta) in their related column. + +Example files samples: +- file A with samples f1, f2, f3, f4, f6 +- file B with samples f2, f4, f5 +- file C with samples f1, f2, f5 + +Example output: + x - computation takes place for pair + b - baseline sample percentage + +- perf diff A B C + + baseline/A compute/B compute/C samples + --------------------------------------- + b x f1 + b x x f2 + b f3 + b x f4 + b f6 + x x f5 + +- perf diff B A C + + baseline/B compute/A compute/C samples + --------------------------------------- + b x x f2 + b x f4 + b x f5 + x x f1 + x f3 + x f6 + +- perf diff C B A + + baseline/C compute/B compute/A samples + --------------------------------------- + b x f1 + b x x f2 + b x f5 + x f3 + x x f4 + x f6 + +COMPARISON METHODS +------------------ +delta +~~~~~ +If specified the 'Delta' column is displayed with value 'd' computed as: + + d = A->period_percent - B->period_percent + +with: + - A/B being matching hist entry from data/baseline file specified + (or perf.data/perf.data.old) respectively. + + - period_percent being the % of the hist entry period value within + single data file + + - with filtering by -C, -d and/or -S, period_percent might be changed + relative to how entries are filtered. Use --percentage=absolute to + prevent such fluctuation. + +ratio +~~~~~ +If specified the 'Ratio' column is displayed with value 'r' computed as: + + r = A->period / B->period + +with: + - A/B being matching hist entry from data/baseline file specified + (or perf.data/perf.data.old) respectively. + + - period being the hist entry period value + +wdiff:WEIGHT-B,WEIGHT-A +~~~~~~~~~~~~~~~~~~~~~~~ +If specified the 'Weighted diff' column is displayed with value 'd' computed as: + + d = B->period * WEIGHT-A - A->period * WEIGHT-B + + - A/B being matching hist entry from data/baseline file specified + (or perf.data/perf.data.old) respectively. + + - period being the hist entry period value + + - WEIGHT-A/WEIGHT-B being user suplied weights in the the '-c' option + behind ':' separator like '-c wdiff:1,2'. + - WIEGHT-A being the weight of the data file + - WIEGHT-B being the weight of the baseline data file + SEE ALSO -------- -linkperf:perf-record[1] +linkperf:perf-record[1], linkperf:perf-report[1] |