Re: [PATCH 3/4] perf, x86: Use ALTERNATIVE() to check forX86_FEATURE_PERFCTR_CORE

[Robert Richter]

On 18.04.11 16:00:57, Andi Kleen wrote:
> Robert Richter <robert.richter@xxxxxxx> writes:
> 
> > Using ALTERNATIVE() when checking for X86_FEATURE_PERFCTR_CORE avoids
> > an extra pointer chase and data cache hit.
> 
> Is that really a performance critical path?
> 
> Seems more like unnecessary obfuscation to me.

We hotest path is in perf_pmu_disable(), which happens at least with
every task switch when calling the event scheduler.

-Robert

-- 
Advanced Micro Devices, Inc.
Operating System Research Center

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