linux-kernel - Re: RFC: revert request for cpuidle patches e11538d1 and 69a37bea

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Message-ID: <51F2BC31.7000407@redhat.com>
Date:	Fri, 26 Jul 2013 14:13:05 -0400
From:	Rik van Riel <riel@...hat.com>
To:	Jeremy Eder <jeder@...hat.com>
CC:	linux-kernel@...r.kernel.org, rafael.j.wysocki@...el.com,
	youquan.song@...el.com, paulmck@...ux.vnet.ibm.com,
	daniel.lezcano@...aro.org, arjan@...ux.intel.com,
	len.brown@...el.com
Subject: Re: RFC:  revert request for cpuidle patches e11538d1 and 69a37bea

On 07/26/2013 01:33 PM, Jeremy Eder wrote:
> Hello,
>
> We believe we've identified a particular commit to the cpuidle code that
> seems to be impacting performance of variety of workloads.  The simplest way to
> reproduce is using netperf TCP_RR test, so we're using that, on a pair of
> Sandy Bridge based servers.  We also have data from a large database setup
> where performance is also measurably/positively impacted, though that test
> data isn't easily share-able.
>
> Included below are test results from 3 test kernels:
>
> kernel       reverts
> -----------------------------------------------------------
> 1) vanilla   upstream (no reverts)
>
> 2) perfteam2 reverts e11538d1f03914eb92af5a1a378375c05ae8520c
>
> 3) test      reverts 69a37beabf1f0a6705c08e879bdd5d82ff6486c4
>                       e11538d1f03914eb92af5a1a378375c05ae8520c
>
> In summary, netperf TCP_RR numbers improve by approximately 4% after
> reverting 69a37beabf1f0a6705c08e879bdd5d82ff6486c4.  When
> 69a37beabf1f0a6705c08e879bdd5d82ff6486c4 is included, C0 residency never
> seems to get above 40%.  Taking that patch out gets C0 near 100% quite
> often, and performance increases.

Could you try running the tests with just the repeat mode
stuff from commit 69a37bea excluded, but leaving the common
infrastructure and commit e11538?

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