linux-kernel - Re: [PATCH V3]hrtimer: Fix a performance regression by disable reprogramming in remove

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Date:	Thu, 12 Dec 2013 22:14:11 +0800
From:	Ethan Zhao <ethan.kernel@...il.com>
To:	Mike Galbraith <bitbucket@...ine.de>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>, rjw@...k.pl,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	linux-pm@...r.kernel.org, Len Brown <lenb@...nel.org>
Subject: Re: [PATCH V3]hrtimer: Fix a performance regression by disable
 reprogramming in remove_hrtimer

Mike,
    it seems the IPI issue got root cause (cpu hardware errata ) now ?
I only catch some pieces of the mails, is that to say the crazy horse
made by Intel will wake up unexpected, and eat too much reschedule
IPI, then the horse got hotter, performance down, and so the fix would
be a 'CFLUSH' to all the buggy CPU, is that right ?

Thanks,
Ethan





On Mon, Oct 7, 2013 at 12:57 PM, Ethan Zhao <ethan.kernel@...il.com> wrote:
> Got it.
>
> On Mon, Oct 7, 2013 at 12:41 PM, Mike Galbraith <bitbucket@...ine.de> wrote:
>> On Fri, 2013-10-04 at 20:06 +0800, Ethan Zhao wrote:
>>> Mike, Peter,
>>>    Seems lots of work has been done these days, studious guys. those
>>> patches merged in last stable/dev branch (fix performance regression
>>> caused by extra rtimer programming and rescheduling IPI,confusing
>>> idle... etc) ? So I could just do a lazy pull for test with my
>>> environment.  I need catch up with other mail loops with my vacation
>>> again.
>>
>> Massive timer overhead seems to have crawled off and died while I wasn't
>> looking.  Peter's fix for IPI woes..
>>
>> tip commit ea811747 sched, idle: Fix the idle polling state logic
>>
>> ..hasn't yet swum upstream.
>>
>> -Mike
>>
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