Re: [PATCH] sched: wake-affine throttle

From: Michael Wang
Date: Thu Apr 11 2013 - 23:17:58 EST


On 04/10/2013 04:51 PM, Peter Zijlstra wrote:
> On Wed, 2013-04-10 at 11:30 +0800, Michael Wang wrote:
>> | 15 GB | 32 | 35918 | | 37632 | +4.77% | 47923 | +33.42% |
>> 52241 | +45.45%
>
> So I don't get this... is wake_affine() once every milisecond _that_
> expensive?
>
> Seeing we get a 45%!! improvement out of once every 100ms that would
> mean we're like spending 1/3rd of our time in wake_affine()? that's
> preposterous. So what's happening?

Hi, Peter

I think Mike has very well explained the reason why throttle bring us
benefit and why the benefit looks so significant when interval get
higher, could you please take a look at his mail and see whether it
addressed this concern?

And thanks Mike again for the excellent analysis :)

Regards,
Michael Wang


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