From: Mike Galbraith <efault@gmx.de>
To: tglx@linutronix.de
Cc: Andrew Morton <akpm@linux-foundation.org>,
Ingo Molnar <mingo@elte.hu>, john stultz <johnstul@us.ibm.com>,
Roman Zippel <zippel@linux-m68k.org>,
Ken Chen <kenneth.w.chen@intel.com>,
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 10:16:18 +0100 [thread overview]
Message-ID: <1172135778.11226.10.camel@Homer.simpson.net> (raw)
In-Reply-To: <1172104409.25076.165.camel@localhost.localdomain>
On Thu, 2007-02-22 at 01:33 +0100, Thomas Gleixner wrote:
> Problem description at:
> http://bugzilla.kernel.org/show_bug.cgi?id=8048
>
> Commit b18ec80396834497933d77b81ec0918519f4e2a7
> [PATCH] sched: improve migration accuracy
> optimized the scheduler time calculations, but broke posix-cpu-timers.
>
> 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.
Oops, missed that. You could also remove the prev->last_ran assignment
just above your addition, and turn this into a negative cost bugfix :)
-Mike
next prev parent reply other threads:[~2007-02-22 9:16 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
2007-02-22 9:16 ` Mike Galbraith [this message]
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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