From: Zhang, Yanmin <yanmin_zhang@linux.intel.com>
Date: Thu, 18 Mar 2010 14:36:03 +0000 (-0300)
Subject: perf stat: Enable counters when collecting process-wide or system-wide data
X-Git-Tag: v2.6.35-rc1~522^2~173
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6be2850effd6a8bae11d623c8c52e88d2fbc0e96;p=pandora-kernel.git

perf stat: Enable counters when collecting process-wide or system-wide data

Command 'perf stat' doesn't enable counters when collecting an
existing (by -p) process or system-wide statistics. Fix the
issue.

Change the condition of fork/exec subcommand. If there is a
subcommand parameter, perf always forks/execs it. The usage
example is:

 # perf stat -a sleep 10

So this command could collect statistics for 10 seconds
precisely. User still could stop it by CTRL+C. Without the new
capability, user could only use CTRL+C to stop it without
precise time clock.

Another issue is 'perf stat -a' consumes 100% time of a full
single logical cpu. It has a bad impact on running workload.

Fix it by adding a sleep(1) in the while(!done) loop in function
run_perf_stat.

Signed-off-by: Zhang Yanmin <yanmin_zhang@linux.intel.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Sheng Yang <sheng@linux.intel.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Jes Sorensen <Jes.Sorensen@redhat.com>
Cc: Gleb Natapov <gleb@redhat.com>
Cc: Zachary Amsden <zamsden@redhat.com>
Cc: <zhiteng.huang@intel.com>
LKML-Reference: <1268922965-14774-1-git-send-email-acme@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---

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