linux-kernel - Re: [BUG] sched: clock wrap bug in 2.6.35-stable kills scheduling

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Message-ID: <1340652807.21991.19.camel@twins>
Date:	Mon, 25 Jun 2012 21:33:27 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Thomas Lange <thomas@...elatus.se>
Cc:	mingo@...hat.com, gregkh@...uxfoundation.org,
	linux-kernel@...r.kernel.org
Subject: Re: [BUG] sched: clock wrap bug in 2.6.35-stable kills scheduling

On Mon, 2012-06-25 at 20:49 +0200, Thomas Lange wrote:
> Commit fe44d62 removed the if-clause that caused the problem. Most likely, this
> solved the problem.

Ah, probably. IIRC we also fixed the short wrap of those arm clocks
since.

> > If anything, I think something like the below ought to cure things.
> 
> I agree. Either we make sure that sched_clock() never wraps or if it wraps,
> that it wraps shortly after boot to catch problems early.

Right, sched_clock() should only ever wrap on the full u64.
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