Re: [PATCH v2] sched: async unthrottling for cfs bandwidth

[Michal Koutný]

On Wed, Nov 02, 2022 at 05:10:08PM -0700, Josh Don <joshdon@xxxxxxxxxx> wrote:
> Without my patch, distribute_cfs_runtime() will unthrottle the
> cfs_rq's, and as you point out, it doesn't actually give them any real
> quota, it lets assign_cfs_rq_runtime() take care of that. But this
> happens asynchronously on those cpus. If they are idle, they wait for
> an IPI from the resched_curr() in unthrottled_cfs_rq(), otherwise they
> simply wait until potentially the next rescheduling point. So we are
> currently far from ever being guaranteed that the order the cpus pull
> actual quota via assign_cfs_rq_runtime() matches the order they were
> unthrottled from the list.

Thanks for breaking it down, I agree your change won't affect the
fairness substantially and my other points are clarified too.

Michal

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