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Commit 3a3beae8 authored by Jiri Olsa's avatar Jiri Olsa Committed by Arnaldo Carvalho de Melo
Browse files

perf diff: Update perf diff documentation for multiple data comparison 



Updating perf diff documentation to include multiple perf data files
comparison.

Signed-off-by: default avatarJiri Olsa <jolsa@redhat.com>
Reviewed-by: default avatarNamhyung Kim <namhyung@kernel.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-tr6su3wfm20k2m5npjggyvtw@git.kernel.org


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 22aeb7f5

tools/perf/Documentation/perf-diff.txt

+64 −9
Original line number Diff line number Diff line
@@ -3,17 +3,17 @@ 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.
@@ -87,6 +87,59 @@ OPTIONS 
--formula::

        Show formula for given computation.



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
@@ -96,7 +149,7 @@ 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 first/second file specified

  - 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
@@ -109,24 +162,26 @@ 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 first/second file specified

  - 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

~~~~~

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 first/second file specified

  - 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

--------