linux-kernel - Re: [PATCH v2 1/3] process cputimer is moving faster than its corresponding clock

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Message-ID: <CAFTL4hwxW9dGZH0rWOAngpYd1DJMGHAF7002weA4stNv6n4t6Q@mail.gmail.com>
Date:	Mon, 29 Apr 2013 02:45:55 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Olivier Langlois <olivier@...llion01.com>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>, schwidefsky@...ibm.com,
	Steven Rostedt <rostedt@...dmis.org>,
	KOSAKI Motohiro <kosaki.motohiro@...il.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/3] process cputimer is moving faster than its
 corresponding clock

2013/4/27 Olivier Langlois <olivier@...llion01.com>:
>
>
> Forbids the cputimer to drift ahead of its process clock by
> blocking its update when a tick occurs while a autoreaping task
> is currently in do_exit() between the call to release_task() and
> its final call to schedule().
>
> Any task stats update after having called release_task() will
> be lost because they are added to the global process stats located
> in the signal struct from release_task().
>
> Ideally, you should postpone the release_task() call after the
> final context switch to get all the stats added but this is
> more complex to achieve.
>
> In other words, this is slowing down the cputimer so it keep the same
> pace than the process clock but in fact, what should be done is to
> speed up the process clock by adding the missing stats to it.
>
> Signed-off-by: Olivier Langlois <olivier@...llion01.com>

Thanks.

Could you please resend these three patches in a new mail thread to
make reviews easier? Also it would be nice to propose a different
subject for each individual patch. Each of which describing what the
patch does in a few words.

Thanks.
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