Re: [PATCH] sched/fair: improve spreading of utilization

[Valentin Schneider]

On Fri, Mar 13 2020, Vincent Guittot wrote:
>> My point is that if we prevent this for migrate_util, it would make
>> sense to prevent it for migrate_task, but it's not straightforward since
>
> hmm but we don't want to prevent this active balance for migrate_task
> because of cases like the one you mentioned above.
>
> we might consider to finally select a CPU with only 1 running task
> with migrate_util if there is no other CPU with more than 1 task. But
> this would complexify the code and I don't think it's possible because
> migrate_util is used to pull some utilizations from an overloaded
> group which must have a CPU with a waiting task to be overloaded.
>

OK, so what we may want in the future is a tighter link between
find_busiest_queue() and voluntary_active_balance(). I don't see a neat
way of doing this right now, I'll ponder over it.

Thanks for keeping up with my rambling.