Messages in this thread | | | Subject | Re: high power consumption in recent kernels | From | Peter Zijlstra <> | Date | Thu, 08 Jul 2010 17:59:39 +0200 |
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On Thu, 2010-07-08 at 15:23 +0200, Peter Zijlstra wrote: > On Thu, 2010-07-08 at 21:46 +0900, Norbert Preining wrote: > > Looks promising, reverting the old patch, adding that one, building, > > running, unplugging ppower, powertop runs now since some time, > > it seems that we are back to better situation: > > Hrmm, Mike seems you wrecked power usage.. > > So nohz_ratelimit() prevents us from entering NOHZ when the last attempt > was less than 1/2 a jiffy ago (fwiw: NSEC_PER_SEC/HZ == TICK_NSEC). > > Its either entering idle or irq_exit trying to enter nohz state, if we > keep skipping it it means that we get enough interrupt activity to > render nohz useless anyway.. so not quite sure how this wrecks things..
OK, so Arjan said the gain could come from tricking the idle governor into not using deeper C states. He also said he significantly cured said governor in .35.
Mike could you re-run your netperf tests that showed the 10% throughput gain? Hopefully the fixed governor will yield the same result and we can kill off this ratelimit thing.
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