Re: [PATCH 2/3] sched/fair: Correctly insert cfs_rq's to list on unthrottle

[Odin Ugedal]

Hi,

> normally tg_load_avg_contrib should be null when cfs_rq_is_decayed()

Yeah, I think that is an ok assumption of how it _should_ work (given
the other patches in flight are merged).

> The reason of this list is to ensure that the load of all cfs_rq are
> periodically updated  as it is then used to share the runtime between
> groups so we should keep to use the rule whenever possible.

Yeah, right.

> we probably need to keep (cfs_rq->nr_running >= 1) as we can have case
> where tg_load_avg_contrib is null but a task is enqueued

Yeah, there is probably a chance of enqueuing a task without any load,
and then a parent gets throttled.
So (cfs_rq->tg_load_avg_contrib || cfs_rq->nr_running) is probably the
way to go if we want to avoid
a new field. Will resend a patch with that instead.

In case the new field is the main issue with the original solution, we
could also change the on_list int to have three modes like; NO, YES,
THROTTLED/PAUSED, but that would require a bigger rewrite of the other
logic, so probably outside the scope of this patch.

Thanks
Odin