On Fri, 28 May 2021 at 17:07, Odin Ugedal <odin@xxxxxxx> wrote: > > Hi, > > > What would be the other condition in addition to the current one > > :cfs_rq->nr_running >= 1 ? > > The condition is that if it has load, we should add it (I don't have > 100% control on util_avg and runnable_avg tho.). Using > "!cfs_rq_is_decayed()" is another way, but imo. that is a bit > overkill. normally tg_load_avg_contrib should be null when cfs_rq_is_decayed() > > > We need to add a cfs_rq in the list if it still contributes to the > > tg->load_avg and the split of the share. Can't we add a condition for > > this instead of adding a new field ? > > Yes, using cfs_rq->tg_load_avg_contrib as below would also work the > same way. I still think being explicit that we insert it if we have > removed it is cleaner in a way, as it makes it consistent with the > other use of list_add_leaf_cfs_rq() and list_del_leaf_cfs_rq(), but 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. > that is about preference I guess. I do however think that using > tg_load_avg_contrib will work just fine, as it should always be > positive in case the cfs_rq has some load. I can resent v2 of this > patch using this instead; > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index ad7556f99b4a..969ae7f930f5 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -4720,7 +4720,7 @@ static int tg_unthrottle_up(struct task_group > *tg, void *data) > cfs_rq->throttled_clock_task; > > /* Add cfs_rq with already running entity in the list */ > - if (cfs_rq->nr_running >= 1) > + if (cfs_rq->tg_load_avg_contrib) 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 > list_add_leaf_cfs_rq(cfs_rq); > }
