From: Thomas Gleixner <tglx@linutronix.de>
To: Ingo Molnar <mingo@elte.hu>
Cc: Andrew Morton <akpm@linux-foundation.org>,
john stultz <johnstul@us.ibm.com>,
Roman Zippel <zippel@linux-m68k.org>,
Mike Galbraith <efault@gmx.de>,
balducci@units.it, LKML <linux-kernel@vger.kernel.org>,
Greg KH <greg@kroah.com>
Subject: Re: [PATCH] Fix posix-cpu-timer breakage caused by stale p->last_ran value
Date: Thu, 22 Feb 2007 09:01:39 +0100 [thread overview]
Message-ID: <1172131299.25076.168.camel@localhost.localdomain> (raw)
In-Reply-To: <20070222074624.GA9800@elte.hu>
On Thu, 2007-02-22 at 08:46 +0100, Ingo Molnar wrote:
> * Thomas Gleixner <tglx@linutronix.de> wrote:
>
> > The problem is that the p->last_ran value is not updated after a
> > context switch. So a subsequent call to current_sched_time()
> > calculates with a stale p->last_ran value, i.e. accounts the full
> > time, which the task was scheduled away.
> >
> > Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
>
> > sched_info_switch(prev, next);
> > if (likely(prev != next)) {
> > - next->timestamp = now;
> > + next->timestamp = next->last_ran = now;
>
> ouch! nice catch. Also for v2.6.20.2 i think. 2.6.19 should be
> unaffected.
Yes, was introduced in 2.6.20 and definitely should hit the stable tree.
tglx
next prev parent reply other threads:[~2007-02-22 7:56 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20070221104747.3cb0da32.akpm@linux-foundation.org>
2007-02-22 0:33 ` Thomas Gleixner
2007-02-22 7:46 ` Ingo Molnar
2007-02-22 8:01 ` Thomas Gleixner [this message]
2007-02-22 9:16 ` Mike Galbraith
2007-03-01 23:45 ` Chuck Ebbert
2007-03-02 0:27 ` Andrew Morton
[not found] <fa.5d4W3Gwb5Gw7ztDfk2utJt1zgjc@ifi.uio.no>
[not found] ` <fa.cIP2OCge0gIF8cSETEmZ9D2dxpE@ifi.uio.no>
2007-02-22 16:49 ` John
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