On 04/08/2020 09:12, Jiang Biao wrote: > If a se is on_rq when reweighting entity, all we need should be > updating the load of cfs_rq, other dequeue/enqueue works could be > redundant, such as, > * account_numa_dequeue/account_numa_enqueue > * list_del/list_add from/into cfs_tasks > * nr_running--/nr_running++
I think this could make sense. Have you spotted a code path where this gives you a change? I guess only for a task on the rq, so: entity_is_task(se) && se->on_rq > Just simplfy the work. Could be helpful for the hot path. IMHO hotpath is update_cfs_group() -> reweight_entity() but this is only called for '!entity_is_task(se)'. See 3290 if (!gcfs_rq) 3291 return; in update_cfs_group(). The 'entity_is_task(se)' case is set_load_weight(struct task_struct *p, ...) -> reweight_task(p, ...) -> reweight_entity(..., &p->se, ...) but here !se->on_rq. > Signed-off-by: Jiang Biao <benbji...@tencent.com> > --- > kernel/sched/fair.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 04fa8dbcfa4d..18a8fc7bd0de 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -3086,7 +3086,7 @@ static void reweight_entity(struct cfs_rq *cfs_rq, > struct sched_entity *se, > /* commit outstanding execution time */ > if (cfs_rq->curr == se) > update_curr(cfs_rq); > - account_entity_dequeue(cfs_rq, se); > + update_load_sub(&cfs_rq->load, se->load.weight); > } > dequeue_load_avg(cfs_rq, se); > > @@ -3102,7 +3102,7 @@ static void reweight_entity(struct cfs_rq *cfs_rq, > struct sched_entity *se, > > enqueue_load_avg(cfs_rq, se); > if (se->on_rq) > - account_entity_enqueue(cfs_rq, se); > + update_load_add(&cfs_rq->load, se->load.weight); > > }
