lkml.org 
[lkml]   [2015]   [Apr]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
Subjectperf report broken for branch stack samples
Hello,

perf report is not showing up the branch stack sample results in the
from_symbol ---> to_symbol format even if the perf.data file has got
the samples (through 'perf record -b <workload>' session). Perf report
still displays the generic event based relative symbol classification
as usual. This problem can also be seen on X86. I wonder whether there
is any semantics change in the way perf report auto detects branch stack
samples in the perf.data file and reports in the intended format. After
doing a git bisect session, this following commit seems to have changed
the perf report behavior.

commit fa94c36c29ed8bb4749b5fd7ea51a593f673dcef
Author: Andi Kleen <ak@linux.intel.com>
Date: Wed Nov 12 18:05:22 2014 -0800

perf report: Add --branch-history option

Add a --branch-history option to perf report that changes all the
settings necessary for using the branches in callstacks.

This is just a short cut to make this nicer to use, it does not enable
any functionality by itself.

v2: Change sort order. Rename option to --branch-history to
be less confusing.
v3: Updates
v4: Fix conflict with newer perf base
v5: Port to latest tip
v6: Add more comments. Remove CCKEY_ADDRESS setting. Remove
unnecessary branch_mode setting. Use a boolean.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/1415844328-4884-5-git-send-email-andi@firstfloor.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

I dont have much context of this change but it seems to be using branch
records along with call chain data (provided you have used both -b/-j
and -g option during perf record) to display better control flow graph ?
But then if we have just used -b and not -g then it should still give us
the previous output what we used to get.

Regards
Anshuman



\
 
 \ /
  Last update: 2015-04-01 11:41    [W:0.092 / U:0.568 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site