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

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Date:	Mon, 29 Apr 2013 18:42:25 -0400
From:	KOSAKI Motohiro <kosaki.motohiro@...il.com>
To:	Olivier Langlois <olivier@...llion01.com>
CC:	KOSAKI Motohiro <kosaki.motohiro@...il.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>, schwidefsky@...ibm.com,
	Steven Rostedt <rostedt@...dmis.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/3] process cputimer is moving faster than its corresponding
 clock

>> tick lost doesn't occur an issue. because glibc only test posix conformance and
>> posix allow inacculacy. In other words, timer must not run faster than real clock.
>> but lost and makes slower are accepted in the test.
>>
> What is lost isn't cputimer tick. They are accounted
> account_group_exec_runtime(). What is lost it is what is added to
> curr->sum_exec_runtime. Thus making the thread group clock running
> slower than the cputimer.
> 
> Please spend some time reading the code and less time writing e-mails.
> 
> Read the code of release_task() and where it is called in do_exit().
> 
> Once it is done, it should be clear to you.

After several grepping, I may got your point. Guys, sig->sum_sched_runtime is gathered
in __exit_signal, not release_task() nor do_exit().

So, I'm now convinced your patch is correct. Even though the comments is terribuly misleading.



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