Messages in this thread |  | | | Date | Sat, 12 Sep 2009 16:04:40 +0200 | | From | Arjan van de Ven <> | | Subject | Re: PATCH] cpuidle: A new variant of the menu governor to boost IO performance |
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On Sat, 12 Sep 2009 12:39:39 +0100 Matthew Garrett <mjg59@srcf.ucam.org> wrote:
> 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.
correct.
> 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?
so far, with a 10 msec ondemand interval, there is room for improvement, but it's not too bleak either. With longer intervals there clearly are problems.
I have some patches for that. However the gain is not nearly as clear as with this C state patch, and they need some more tweaking...
-- Arjan van de Ven Intel Open Source Technology Centre For development, discussion and tips for power savings, visit http://www.lesswatts.org
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