linux-kernel - Re: [lkp] [locking/mutexes] cb4bbc457b: -40.0% unixbench.score

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Date:	Thu, 21 Jan 2016 18:48:01 -0800
From:	Davidlohr Bueso <dave@...olabs.net>
To:	kernel test robot <ying.huang@...ux.intel.com>
Cc:	Ding Tianhong <dingtianhong@...wei.com>, lkp@...org,
	LKML <linux-kernel@...r.kernel.org>,
	Waiman Long <Waiman.Long@...com>,
	Tim Chen <tim.c.chen@...ux.intel.com>,
	Jason Low <jason.low2@...com>,
	Will Deacon <will.deacon@....com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"Paul E. McKenney" <paulmck@...ibm.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	0day robot <fengguang.wu@...el.com>
Subject: Re: [lkp] [locking/mutexes] cb4bbc457b: -40.0% unixbench.score

On Fri, 22 Jan 2016, kernel test robot wrote:

>FYI, we noticed the below changes on
>
>https://github.com/0day-ci/linux Ding-Tianhong/locking-mutexes-don-t-spin-on-owner-when-wait-list-is-not-NULL/20160121-173317
>commit cb4bbc457bfed6194ffab1b10c7be73b3f16ca2d ("locking/mutexes: don't spin on owner when wait list is not NULL.")

I'm not sure why this would even be reported, as this patch has not been accepted
or acked or nothin', by anyone. In this particular case that raw performance drop
is because spinning is pretty much disabled by Ding's change. Totally expected for
the kind of workload unixbench triggers.

All this does is hurt lkml-searchability.

Thanks,
Davidlohr