Re: [PATCH 2/4] nohz: Synchronize sleep time stats with seqlock

[Peter Zijlstra]

On Tue, Oct 01, 2013 at 06:47:10PM +0200, Frederic Weisbecker wrote:
> Yeah thinking more about it, the preempt disable was probably not
> necessary. Now that's trading 2 atomics + 1 Lock/Unlock with 2 Lock/Unlock.

It trades the current 2 atomics for 2 LOCK/UNLOCK. And on x86_64 that's
2 atomics.

So all we get is some extra branches; which we must hope for don't
actually mess things up too bad.

Ohh.. wait a sec.. we also call local_clock() which includes another
atomic :/ Bugger.. 


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