linux-kernel - Re: [PATCH v7 0/8] Tunable sched_mc_power

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Date:	Tue, 30 Dec 2008 07:21:39 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Balbir Singh <balbir@...ux.vnet.ibm.com>
Cc:	linux-kernel@...r.kernel.org,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH v7 0/8] Tunable sched_mc_power_savings=n


* Balbir Singh <balbir@...ux.vnet.ibm.com> wrote:

> > > KERNBENCH Runs: make -j4 on a x86 8 core, dual socket quad core cpu
> > > package system
> > >
> > > SchedMC Run Time     Package Idle    Energy  Power
> > > 0       81.68        52.83% 54.71%  1.00x J 1.00y W
> > > 1       80.70        36.62% 70.11%  0.95x J 0.96y W
> > > 2       74.95        19.53% 85.92%  0.90x J 0.98y W

> > Your result is very interesting.
> > level 2 is more fast and efficient of power.
> > 
> > What's major contributor to use less time in level 2?
> > I think it's cache bounce is less time than old.
> > Is right ?
> 
> Yes, correct

yes, i too noticed that runtime improved so dramatically: +7.5% on 
kernbench is a _very_ big deal.

So i wanted to ask you to re-test whether this speedup is reproducible, 
and if yes, please check a few other workloads (for example sysbench on 
postgresql / mysqld) and send a patch that changes the 
sched_mc_power_savings default to POWERSAVINGS_BALANCE_WAKEUP (2).

Sidenote, _please_ fix your mail client to not mess up the Cc: list via:

Mail-Followup-To: MinChan Kim <minchan.kim@...il.com>,
        Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>,
        Linux Kernel <linux-kernel@...r.kernel.org>,
        Suresh B Siddha <suresh.b.siddha@...el.com>,
        Venkatesh Pallipadi <venkatesh.pallipadi@...el.com>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Ingo Molnar <mingo@...e.hu>, Dipankar Sarma <dipankar@...ibm.com>,
        Vatsa <vatsa@...ux.vnet.ibm.com>, Gautham R Shenoy <ego@...ibm.com>,
        Andi Kleen <andi@...stfloor.org>,
        David Collier-Brown <davecb@....com>,
        Tim Connors <tconnors@...ro.swin.edu.au>,
        Max Krasnyansky <maxk@...lcomm.com>,
        Gregory Haskins <gregory.haskins@...il.com>,
        Pavel Machek <pavel@...e.cz>,
        Andrew Morton <akpm@...ux-foundation.org>

	Ingo
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