Messages in this thread | ![/](/images/icornerl.gif) | | Date | Mon, 15 Jan 2024 13:40:54 +0100 | Subject | Re: [PATCH] sched/idle: Prevent stopping the tick when there is no cpuidle driver | From | Pierre Gondois <> |
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Hello Thomas,
On 1/12/24 15:52, Thomas Gleixner wrote: > On Fri, Jan 12 2024 at 14:39, Pierre Gondois wrote: >> On 1/12/24 11:56, Anna-Maria Behnsen wrote: >>> Pierre Gondois <pierre.gondois@arm.com> writes: >>>> I agree that the absence of cpuidle driver prevents from reaching deep >>>> idle states. FWIU, there is however still benefits in stopping the tick >>>> on such platform. >>> >>> What's the benefit? >> >> I did the following test: >> - on an arm64 Juno-r2 platform (2 big A-72 and 4 little A-53 CPUs) >> - booting with 'cpuidle.off=1' >> - using the energy counters of the platforms >> (the counters measure energy for the whole cluster of big/little CPUs) >> - letting the platform idling during 10s >> >> So the energy consumption would be up: >> - ~6% for the big CPUs >> - ~10% for the litte CPUs > > Fair enough, but what's the actual usecase? > > NOHZ w/o cpuidle driver seems a rather academic exercise to me.
I thought Anna-Maria had a use-case for this. I just wanted to point out that this patch could potentially increase the energy consumption for her use-case, nothing more,
Regards, Pierre
> > Thanks, > > tglx
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