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Date: Tue, 23 Apr 2013 12:05:05 +0800
From: Michael Wang <wangyun@linux.vnet.ibm.com>
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To: Ingo Molnar <mingo@kernel.org>
CC: Peter Zijlstra <peterz@infradead.org>, LKML <linux-kernel@vger.kernel.org>,
        Mike Galbraith <efault@gmx.de>, Alex Shi <alex.shi@intel.com>,
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        Andrew Morton <akpm@linux-foundation.org>,
        "Nikunj A. Dadhania" <nikunj@linux.vnet.ibm.com>,
        Ram Pai <linuxram@us.ibm.com>
Subject: Re: [PATCH] sched: wake-affine throttle
References: <5164DCE7.8080906@linux.vnet.ibm.com> <1366626208.2721.12.camel@laptop> <20130422103521.GA14103@gmail.com>
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On 04/22/2013 06:35 PM, Ingo Molnar wrote:
> 
> * Peter Zijlstra <peterz@infradead.org> wrote:
> 
>> OK,.. Ingo said that pipe-test was the original motivation for 
>> wake_affine() and since that's currently broken to pieces due to 
>> select_idle_sibling() is there still a benefit to having it at all?
>>
>> Can anybody find any significant regression when simply killing 
>> wake_affine()?
> 
> I'd suggest doing a patch that does:
> 
>    s/SD_WAKE_AFFINE/0*SD_WAKE_AFFINE

But by doing this, we won't be able to find 'affine_sd' any more, that
will also skip the select_idle_sibling() logical (in current code),
isn't it?

If we really want to kill the stuff (I prefer not...), I suggest we
forbidden the wake-affine by throttle it with an incredible interval,
that's also easily to be reverted :)

Regards,
Michael Wang

> 
> in all the relevant toplogy.h files, but otherwise keep the logic in 
> place. That way it's easy to revert.
> 
> Thanks,
> 
> 	Ingo
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