Re: [RFC PATCH v3 0/3] sched: simplify the select_task_rq_fair()

From: Michael Wang
Date: Fri Feb 22 2013 - 01:06:51 EST


On 02/22/2013 01:08 PM, Mike Galbraith wrote:
> On Fri, 2013-02-22 at 10:37 +0800, Michael Wang wrote:
>
>> According to the testing result, I could not agree this purpose of
>> wake_affine() benefit us, but I'm sure that wake_affine() is a terrible
>> performance killer when system is busy.
>
> (hm, result is singular.. pgbench in 1:N mode only?)

I'm not sure about how pgbench implemented, all I know is it will create
several instance and access the database, I suppose no different from
several threads access database (1 server and N clients?).

There are improvement since when system busy, wake_affine() will be skipped.

And in old world, when system is busy, wake_affine() will only be
skipped if prev_cpu and curr_cpu belong to different nodes.

Regards,
Michael Wang

>
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