Re: [PATCH] intel_idle: use static_key to optimize idle enter/exit paths

From: Len Brown
Date: Mon Jul 28 2014 - 16:38:46 EST

On Fri, Jul 11, 2014 at 1:54 PM, Jason Baron <jbaron@xxxxxxxxxx> wrote:
> If 'arat' is set in the cpuflags, we can avoid the checks for entering/exiting
> the tick broadcast code entirely. It would seem that this is a hot enough code
> path to make this worthwhile. I ran a few hackbench runs, and consistenly see
> reduced branches and cycles.

Hi Jason,

Your logic looks right -- though I've never used this
static_key_slow_inc() stuff.
I'm impressed that something in user-space could detect this change.

Can you share how to run the workload where you detected a difference,
and describe the hardware you measured?

-Len Brown, Intel Open Source Technology Center
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