Re: [PATCH RFC RESEND v2 0/2] Prevent cpufreq update for only task on rq that sleeps

Steve Muckle
2017-09-07T18:11:02Z

On 09/07/2017 09:14 AM, Joel Fernandes wrote:
> I'm planning to rebase this series on Linus's master and post it
> again, but just checking any thoughts about it?
>
> Just to add more context, the reason for not updating the frequency:
>
> - When a last dequeue of a sleeping task happens, it is sufficient to
> update utilization without updating the frequency because if other
> CPUs are busy then their updates will consider the utilization of the
> idle CPU in the shared policy unless sufficient time has passed.
>
> - If the last dequeue of a sleeping task happens while all other CPUs
> in the cluster are idle, then the cluster will likely enter
> cluster-idle soon.

To clarify - when you say "last dequeue of a sleeping task happens"
above, you're referring to the dequeue of the last task running on the
CPU, correct? I.e. the CPU is about to go idle?

It's been a while since I've looked at this area so would like to hold
off for a rebased version to review in further detail. But I think the
concept is valid.

thanks,
steve