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Date: Wed, 11 Sep 2013 20:05:42 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
        Ingo Molnar <mingo@kernel.org>, Andi Kleen <ak@linux.intel.com>,
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        linux-arch <linux-arch@vger.kernel.org>, Len Brown <lenb@kernel.org>,
        Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Subject: Re: [PATCH 2/7] sched: Add NEED_RESCHED to the preempt_count
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On Wed, Sep 11, 2013 at 09:35:08AM -0700, Andy Lutomirski wrote:
> I bet that this improves cross-cpu wakeup latency, too -- the old code
> would presumably wake up the cpu and then immediately interrupt it.

Yeah,. its what clued Mike in to there being a problem.

> It might be nice to rename one or both of need_resched and
> test_need_resched, though -- the difference is somewhat inscrutable.

I agreed, I've just been unable to come up with anything sane.

The best I could come up with is renaming
{set,clear,test}_need_resched() to {}_tif_need_resched(), so we then end
up with test_tif_need_resched(), which is slightly more different from
need_resched().

Ideas?