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 14:20:31 -0400
From:	Olivier Langlois <olivier@...llion01.com>
To:	KOSAKI Motohiro <kosaki.motohiro@...il.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>,
	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


> 
> >> I'm confused. glibc's rt/tst-cputimer1 doesn't have thread exiting code. I have
> >> no seen any issue in this accounting.
> > 
> > glibc launch a helper thread to receive timer signal and will also
> > create a new thread upon signal reception when a timer is created with
> > sigev_notify = SIGEV_THREAD;
> > 
> > please see:
> > 
> > glibc-2.17/nptl/sysdeps/unix/sysv/linux/timer_create.c
> > glibc-2.17/nptl/sysdeps/unix/sysv/linux/timer_routines.c
> 
> I know. I taled thread exiting. not thread creating. And, as far as I can see, only test sig1 can fail,
> not thr[12].
> 
Apart from glibc helper thread, the threads created for handling timer
firing all do exit immediatly as soon as user callback returns.

I count 12 thread exits during tst-cputimer1 execution. The errors do
add up hence you're more likely to see errors after 2.5 sec and up from
start of execution. I have seen sig1, thr[12] fails. I see no reason why
one could not fail.


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