Messages in this thread | | | Date | Fri, 6 Mar 2009 09:53:33 +0530 | From | Arun R Bharadwaj <> | Subject | Re: [v2 PATCH 0/4] timers: framework for migration between CPU |
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* Arjan van de Ven <arjan@infradead.org> [2009-03-05 16:14:51]:
> On Wed, 4 Mar 2009 17:42:49 +0530 > Arun R Bharadwaj <arun@linux.vnet.ibm.com> wrote: > > With the timers queued I measure the sleep state residency > > for a period of 10s. > > Next, I enable timer migration and measure the sleep state > > residency period. > > is your table in seconds? Because realistically, at least on PC like > hardware, doing work to get sleep times over a 100 / 200 msecs or so > isn't going to save you any amount of measurable power anymore... >
Hi Arjan,
Yes, the table is in seconds. Rather than looking at timer migration as a direct means of obtaining power savings, I would like to see it as one of the mechanisms which would aid in preventing an almost idle cpu from waking up unnecessarily, thereby causing power penalty. Otherwise, there is a chance of all the CPUs in a particular package being idle and the entire package going into deep sleep. So we cannot really get big power savings just by doing timer migration alone.
--arun
> > > -- > 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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