linux-kernel - Re: [3.6-rc1] sched: clock counts too quickly

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Date:	Sat, 4 Aug 2012 21:10:32 +0900
From:	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
To:	linux-kernel@...r.kernel.org
Cc:	mingo@...hat.com, peterz@...radead.org, tglx@...utronix.de
Subject: Re: [3.6-rc1] sched: clock counts too quickly

Tetsuo Handa wrote:
> > Under unknown condition, clock starts counting up too quickly which is enough
> > to confuse hangcheck timer to print stall warning.
> I wrote a test program.

I suspected that this is a problem within adjtimex() because strace reported clock
jump at adjtimex(). But I've just hit this problem with settimeofday() alone.

---------- test program 2 start ----------
#include <sys/timex.h>

int main(int argc, char *argv[])
{
        while (1) {
                struct timeval tv;
                struct timezone tz;
                gettimeofday(&tv, &tz);
                settimeofday(&tv, &tz);
        }
        return 0;
}
---------- test program 2 end ----------

Regards.
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