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SubjectRe: [PATCH] x86: Use asm-goto to implement mutex fast path on x86-64
On Sat, Jun 29, 2013 at 04:56:30PM -0700, Wedson Almeida Filho wrote:
> On Fri, Jun 28, 2013 at 7:09 AM, Borislav Petkov <> wrote:
> > Btw, do we have any perf data showing any improvements from this patch?
> I wrote a simple test the measures the time it takes to acquire and
> release an uncontended mutex (i.e., we always take the fast path)
> 100k times. I ran it a few times, the original code averages
> 2.743436ms, and the new code averages 2.101098ms, so it's about 23% improvement.

Microbenchmark results tend to be misleading in such situations. Rather,
it would be much closer to reality if you traced a real workload like a
simple kernel build, for example, with and without your patch.

I.e., something like

perf stat --repeat 5 ./

and take a look at what the perfcouters are saying in both cases.

> I also think the code looks cleaner this way.

No doubt.


Sent from a fat crate under my desk. Formatting is fine.

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