linux-kernel - Re: [PATCH 4/7] locking/pvqspinlock: Collect slowpath lock statistics

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Message-ID: <55A55981.3040601@hp.com>
Date:	Tue, 14 Jul 2015 14:48:33 -0400
From:	Waiman Long <waiman.long@...com>
To:	Peter Zijlstra <peterz@...radead.org>
CC:	Ingo Molnar <mingo@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	linux-kernel@...r.kernel.org, Scott J Norton <scott.norton@...com>,
	Douglas Hatch <doug.hatch@...com>
Subject: Re: [PATCH 4/7] locking/pvqspinlock: Collect slowpath lock statistics

On 07/12/2015 04:22 AM, Peter Zijlstra wrote:
> On Sat, Jul 11, 2015 at 04:36:55PM -0400, Waiman Long wrote:
>> This patch enables the accumulation of kicking and waiting related
>> PV qspinlock statistics when the new QUEUED_LOCK_STAT configuration
>> option is selected. It also enables the collection of kicking and
>> wakeup latencies which have a heavy dependency on the CPUs being used.
>>
>> The measured latencies for different CPUs are:
>>
>> 	CPU		Wakeup		Kicking
>> 	---		------		-------
>> 	Haswell-EX	26.4us		 9.2us
>> 	Westmere-EX	99.4US		25.5us
>>
>> So Haswell is much faster than Westmere.
>>
>> The accumulated lock statistics will be reported in debugfs under the
>> pv-qspinlock directory.
> You've again stuck this behind non-trivial patches :-(

I will move that patch into the front in the new patchset.

Cheers,
Longman
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