linux-kernel - Re: [PATCH v5] sched: Avoid unnecessary work in reweight

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Date:	Mon, 20 Feb 2012 14:08:31 +0100
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	Michael Wang <wangyun@...ux.vnet.ibm.com>
Cc:	Ingo Molnar <mingo@...e.hu>, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5] sched: Avoid unnecessary work in reweight_entity

On Sat, 2012-02-18 at 09:43 +0800, Michael Wang wrote:
> And as reight_entity is invoked very often, I think this patch can do some help to the 
> performance, although there are no numbers, we can prove it logically :)  

Well, you're probably right (although I think you completely ignored the
optimizing compiler), but still it would be good to get some numbers to
confirm reality :-)

Just pick your favourite cgroup workload/benchmark and run a pre/post
comparison, possible using perf record.

If all squares up you should see an improvement in your benchmark score
as well as see a reduction in time spend in the function you're
patching.
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