linux-kernel - Re: [PATCH] perf/sched: fix for getting task's execute time

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Message-ID: <1260097609.7818.349.camel@laptop>
Date:	Sun, 06 Dec 2009 12:06:49 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	Xiao Guangrong <xiaoguangrong@...fujitsu.com>
Cc:	Ingo Molnar <mingo@...e.hu>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Paul Mackerras <paulus@...ba.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] perf/sched: fix for getting task's execute time

On Sun, 2009-12-06 at 12:05 +0100, Peter Zijlstra wrote:
> On Sun, 2009-12-06 at 18:57 +0800, Xiao Guangrong wrote:
> > In current code, we get task's execute time by reading
> > "/proc/<pid>/sched" file, it's wrong if the task is created
> > by pthread_create(), because every thread task has same pid.
> > So, the correct way is reading "/proc/<ppid>/task/<tid>/sched"
> > file.
> > 
> > This patch also remove redundant include files since <sys/types.h>
> > is included in "perf.h"
> 
> We really should not be using these proc files but instead make sure
> this information gets transferred through a tracepoint or similar.
> 
> Reading these proc files is too prone to races.

We can probably get the runtime by grouping a task-clock swcounter with
an appropriate other event.

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