linux-kernel - Re: is minimum udelay() not respected in preemptible SMP kernel-2.6.23?

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Date:	Thu, 8 Nov 2007 00:10:44 +0100
From:	Andi Kleen <ak@...e.de>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Marin Mitov <mitov@...p.bas.bg>, linux-kernel@...r.kernel.org,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...e.hu>
Subject: Re: is minimum udelay() not respected in preemptible SMP kernel-2.6.23?


> Ow.  Yes, from my reading delay_tsc() can return early (or after
> heat-death-of-the-universe) if the TSCs are offset and if preemption
> migrates the calling task between CPUs.
>
> I suppose a lameo fix would be to disable preemption in delay_tsc().

Yes. Can't think of any better reasonable fix.

-Andi
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