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Date: Sat, 12 Sep 2009 12:39:39 +0100
From: Matthew Garrett <mjg59@srcf.ucam.org>
To: Arjan van de Ven <arjan@infradead.org>
Cc: linux-kernel@vger.kernel.org, lenb@kernel.org, mingo@elte.hu,
       akpm@linux-foundation.org, peterz@infradead.org,
       yanmin_zhang@linux.intel.com, torvalds@linux-foundation.org,
       jens.axboe@oracle.com
Subject: Re: PATCH] cpuidle: A new variant of the menu governor to boost IO
	performance
Message-ID: <20090912113939.GA7119@srcf.ucam.org>
References: <20090911174019.1ed02737@infradead.org> <20090911220309.GB30989@srcf.ucam.org> <20090912052647.3b6dcb78@infradead.org>
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On Sat, Sep 12, 2009 at 05:26:47AM +0200, Arjan van de Ven wrote:
> On Fri, 11 Sep 2009 23:03:09 +0100
> Matthew Garrett <mjg59@srcf.ucam.org> wrote:
> 
> > When you say that a bit more power was used, is that instantaneous
> > power draw or total power consumption over the run of the benchmark?
> > I'd have expected that completing it 50% faster and then going idle
> > would be a win overall.
> 
> I meant power, not total energy :-)
> 
> in terms of energy it's a win if you only do a fixed amount of work...

Ok, so not really a downside. Not entirely relatedly, we've also seen io 
throughput issues related to P-states - using ondemand, we get reduced 
throughput until the number of clients becomes high enough to push the 
system into a higher P state. Is this something you've been able to 
measure?

-- 
Matthew Garrett | mjg59@srcf.ucam.org
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