Message-ID: <559BD6C6.8070104@fb.com>
Date: Tue, 7 Jul 2015 09:40:22 -0400
From: Josef Bacik <jbacik@fb.com>
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To: Mike Galbraith <umgwanakikbuti@gmail.com>
CC: Peter Zijlstra <peterz@infradead.org>, <riel@redhat.com>,
        <mingo@redhat.com>, <linux-kernel@vger.kernel.org>,
        <morten.rasmussen@arm.com>, kernel-team <Kernel-team@fb.com>
Subject: Re: [patch] Re: [PATCH RESEND] sched: prefer an idle cpu vs an idle
 sibling for BALANCE_WAKE
References: <1432761736-22093-1-git-send-email-jbacik@fb.com>	 <20150528102127.GD3644@twins.programming.kicks-ass.net>	 <20150528110514.GR18673@twins.programming.kicks-ass.net>	 <1434087305.3674.26.camel@gmail.com> <5581B70D.2000800@fb.com>	 <1434588939.3444.25.camel@gmail.com> <55823F33.7040005@fb.com>	 <1434600765.3393.9.camel@gmail.com> <55957871.7080906@fb.com>	 <1435905658.6418.52.camel@gmail.com> <1436025462.17152.37.camel@gmail.com>	 <1436080661.22930.22.camel@gmail.com> <1436159590.5850.27.camel@gmail.com>	 <559A91F4.7000903@fb.com> <1436207790.2940.30.camel@gmail.com>	 <559AD9CE.4090309@fb.com> <1436241678.1836.29.camel@gmail.com> <1436262224.1836.74.camel@gmail.com>
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On 07/07/2015 05:43 AM, Mike Galbraith wrote:
> On Tue, 2015-07-07 at 06:01 +0200, Mike Galbraith wrote:
>> On Mon, 2015-07-06 at 15:41 -0400, Josef Bacik wrote:
>>
>>> So the NO_WAKE_WIDE_IDLE results are very good, almost the same as the
>>> baseline with a slight regression at lower RPS and a slight improvement
>>> at high RPS.
>>
>> Good.  I can likely drop the rest then (I like dinky, so do CPUs;).  I'm
>> not real keen on the feature unless your numbers are really good, and
>> odds are that ain't gonna happen.
>
> More extensive testing in pedantic-man mode increased my confidence of
> that enough to sign off and ship the dirt simple version.  Any further
> twiddles should grow their own wings if they want to fly anyway, the
> simplest form helps your real world load, as well as the not so real
> pgbench, my numbers for that below.
>

The WAKE_WIDE_IDLE run was basically the same so I'm good with the KISS 
version.  I'll run that through the load tests this morning and let you 
know how it goes.  I'm still seeing a slight regression at lower RPS, 
but it's like 1-2%, compared to ~15%.  Once load ramps up we're good to 
go, not sure why that is but it may also be my sample size (the cluster 
is only 32 boxes, the minimum for decent results).  Thanks,

Josef

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