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From: Keith Owens <kaos@sgi.com>
To: Andi Kleen <ak@suse.de>
cc: Ingo Molnar <mingo@elte.hu>,
       Michal Piotrowski <michal.k.k.piotrowski@gmail.com>,
       Andrew Morton <akpm@osdl.org>, linux-kernel@vger.kernel.org
Subject: Re: 2.6.16-rc6-mm2 
In-reply-to: Your message of "Tue, 13 Jun 2006 06:56:45 +0200."
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Date: Tue, 13 Jun 2006 15:08:40 +1000
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Andi Kleen (on Tue, 13 Jun 2006 06:56:45 +0200) wrote:
>
>> I have previously suggested a lightweight solution that pins a process
>> to a cpu 
>
>That is preempt_disable()/preempt_enable() effectively
>It's also light weight as much as these things can be.

The difference being that preempt_disable() does not allow the code to
sleep.  There are some places where we want to use cpu local data and
the code can tolerate preemption and even sleeping, as long as the
process schedules back on the same cpu.