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Re: [Xen-devel] [PATCH v5 3/8] qspinlock, x86: Add x86 specific optimization for 2 contending tasks

On Feb 28, 2014 1:30 AM, "Peter Zijlstra" <peterz@xxxxxxxxxxxxx> wrote:
> At low contention the cmpxchg won't have to be retried (much) so using
> it won't be a problem and you get to have arbitrary atomic ops.

Peter, the difference between an atomic op and *no* atomic op is huge.

And Waiman posted numbers for the optimization. Why do you argue with handwaving and against numbers?


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