Messages in this thread | | | Date | Wed, 15 Aug 2012 18:17:51 -0700 | From | Arjan van de Ven <> | Subject | Re: [discussion]sched: a rough proposal to enable power saving in scheduler |
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On 8/15/2012 6:14 PM, Rik van Riel wrote: > On 08/15/2012 10:43 AM, Arjan van de Ven wrote: > >> The easy cop-out is provide the sysadmin a slider. >> The slightly less easy one is to (and we're taking this approach >> in the new P state code we're working on) say "in the default >> setting, we're going to sacrifice up to 5% performance from peak >> to give you the best power savings within that performance loss budget" >> (with a slider that can give you 0%, 2 1/2% 5% and 10%) > > On a related note, I am looking at the c-state menu governor. > > We seem to have issues there, with Linux often going into a much > deeper C state than warranted, which can lead to a fairly steep > performance penalty for some workloads. >
predicting the future is hard. if you pick a too deep C state, you get a certain fixed performance hit if you pick a too shallow C state, you get a pretty large power hit (depending on how long you actually stay idle)
also would need to know hw details; at least on Intel a bunch of things are done by the firmware and some platforms we're not doing the right things as Linux (or BIOS)
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