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Subject: Re: [PATCH] sched: provide scheduler_ipi() callback in response to
 smp_send_reschedule()
From:   Peter Zijlstra <peterz@infradead.org>
To:     Benjamin Herrenschmidt <benh@kernel.crashing.org>
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Date:   Mon, 17 Jan 2011 21:43:03 +0100
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On Tue, 2011-01-18 at 07:31 +1100, Benjamin Herrenschmidt wrote:
> 
> Beware of false positive, I've used "fake" reschedule IPIs in the past
> for other things (like kicking a CPU out of sleep state for unrelated
> reasons). Nothing that I know that is upstream today but some of that
> might come back. I'd like to avoid having to add an atomic to know if
> it's a real reschedule, will the scheduler be smart enough to not bother
> with false positives ? 

Yes it can deal with that, some will be for reschedules, some will be
for ttwu tail ends and x86 too uses this ipi for a few random other
things like kicking kvm out of guest context..