From: Peter Zijlstra <peterz@infradead.org>
To: Dimitri Sivanich <sivanich@sgi.com>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
Mike Galbraith <efault@gmx.de>,
Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>,
Gregory Haskins <ghaskins@novell.com>, Greg KH <greg@kroah.com>,
Nick Piggin <npiggin@suse.de>, Robin Holt <holt@sgi.com>
Subject: Re: 2.6.27.8 scheduler bug - threads not being scheduled for long periods
Date: Mon, 05 Jan 2009 21:55:58 +0100 [thread overview]
Message-ID: <1231188958.11687.12.camel@twins> (raw)
In-Reply-To: <20090105175641.GA17055@sgi.com>
On Mon, 2009-01-05 at 11:56 -0600, Dimitri Sivanich wrote:
> One place we've found this happens is in update_curr(), which calculates a
> delta_exec value as follows:
> delta_exec = (unsigned long)(now - curr->exec_start);
>
> Sometimes this value will be very large, as 'now' (the rq clock time) will
> be less than 'exec_start'. When this happens, __update_curr() will
> calculate a delta_exec_weighted based on this large value and add it to the
> thread's vruntime:
> curr->vruntime += delta_exec_weighted;
So you're saying your rq->clock = sched_clock_cpu(cpu) = sched_clock()
[on ia64] goes backwards?
If so, then that's an architecture bug, sched_clock() must never be seen
to go backwards!
next prev parent reply other threads:[~2009-01-05 20:56 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-01-05 17:56 2.6.27.8 scheduler bug - threads not being scheduled for long periods Dimitri Sivanich
2009-01-05 18:44 ` Gregory Haskins
2009-01-05 18:51 ` Dimitri Sivanich
2009-01-05 18:59 ` Gregory Haskins
2009-01-14 22:34 ` kenneth johansson
2009-01-05 20:55 ` Peter Zijlstra [this message]
2009-01-05 21:54 ` Dimitri Sivanich
2009-01-05 22:36 ` Dimitri Sivanich
2009-01-05 23:02 ` Dimitri Sivanich
2009-01-06 7:36 ` Peter Zijlstra
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