linux-kernel - Re: [RFC v1] Tunable sched_mc_power

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Message-ID: <4863DB29.1020304@firstfloor.org>
Date:	Thu, 26 Jun 2008 20:08:41 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	balbir@...ux.vnet.ibm.com
CC:	Linux Kernel <linux-kernel@...r.kernel.org>,
	svaidy@...ux.vnet.ibm.com,
	Suresh B Siddha <suresh.b.siddha@...el.com>,
	Venkatesh Pallipadi <venkatesh.pallipadi@...el.com>,
	Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Dipankar Sarma <dipankar@...ibm.com>,
	Vatsa <vatsa@...ux.vnet.ibm.com>,
	Gautham R Shenoy <ego@...ibm.com>
Subject: Re: [RFC v1] Tunable sched_mc_power_savings=n


> A user could be an application and certain applications can predict their
> workload.

So you expect the applications to run suid root and change a sysctl?
And what happens when two applications run that do that and they have differing
requirements? Will they fight over the sysctl?

> For example, a database, a file indexer, etc can predict their workload.


A file indexer should run with a high nice level and low priority would ideally always
prefer power saving. But it doesn't currently. Perhaps it should?

> 
> Policies are best known in user land and the best controlled from there.
> Consider a case where the end user might select a performance based policy or a
> policy to aggressively save power (during peak tariff times). With

How many users are going to do that? Seems like a unrealistic case to me.

-Andi
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