Messages in this thread | | | Subject | Re: [PATCH 1/3] sched/fair: Prepare variables for increased precision of EAS estimated energy | From | Lukasz Luba <> | Date | Wed, 7 Jul 2021 12:02:19 +0100 |
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On 7/7/21 11:50 AM, Vincent Guittot wrote: > On Wed, 7 Jul 2021 at 12:41, Lukasz Luba <lukasz.luba@arm.com> wrote: >> >> >> >> On 7/7/21 11:32 AM, Vincent Guittot wrote: >>> On Wed, 7 Jul 2021 at 12:29, Lukasz Luba <lukasz.luba@arm.com> wrote: >>>> >>>> >>>> >>>> On 7/7/21 11:11 AM, Vincent Guittot wrote: >>>>> On Wed, 7 Jul 2021 at 12:06, Lukasz Luba <lukasz.luba@arm.com> wrote: >>>>>> >>>> >>>> [snip] >>>> >>>>>> No. It's in 0.1uW scale, so 800Watts. Which is 16 CPUs * 64Watts >>>>> >>>>> Oh! you want 0.1uW precision .... This doesn't seem realistic at all. >>>>> I'm not even sure that the power model can even reach an accuracy of >>>>> 1mW >>>>> >>>> >>>> True, the EM is registering platform with 1mW precision, but 1uW >>> >>> Do you mean 1uW or 0.1uW ? >> >> In this patch set I've proposed 0.1uW, but I'm open to drop one >> order of magnitude. The 1uW still be good. > > I don't want to underestimate the capabilities of the power model but > I don't see which benefit you will get with 0.1uW precision > With a 1uW precision the long type currently used for the returned > value is fine for 32bits machine AFAICT >
For 1uW and 1.2Watts for one core, 4 CPUs in cluster we get: (1200 * 1000) * (4 * 1024) = ~4.9bln so it would need div 64 version
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