[PATCH 09/14] perf diff: Update perf diff documentation for multiple data comparison

Jiri Olsa
2012-11-28T13:53:57Z

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

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
---
tools/perf/Documentation/perf-diff.txt | 73 +++++++++++++++++++++++++++++-----
1 file changed, 64 insertions(+), 9 deletions(-)

diff --git a/tools/perf/Documentation/perf-diff.txt b/tools/perf/Documentation/perf-diff.txt
index 194f37d..ab5b79e 100644
--- a/tools/perf/Documentation/perf-diff.txt
+++ b/tools/perf/Documentation/perf-diff.txt
@@ -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.

@@ -91,6 +91,59 @@ 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
@@ -100,7 +153,7 @@ 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
@@ -113,24 +166,26 @@ 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
--------
--
1.7.11.7