On Fri, Nov 06, 2020 at 11:22:03AM +0800, Xuewen Yan wrote: > According to the original code logic: > cfs_rq->avg.util_avg > sa->util_avg = -------------------- * se->load.weight > cfs_rq->avg.load_avg > but for fair_sched_class in 64bits platform: > se->load.weight = 1024 * sched_prio_to_weight[prio]; > cfs_rq->avg.util_avg > so the -------------------- must be extremely small, the > cfs_rq->avg.load_avg > judgment condition "sa->util_avg < cap" could be established. > It's not fair for those tasks who has smaller nice value. > > Signed-off-by: Xuewen Yan <[email protected]> > --- > changes since V2: > > *kernel/sched/fair.c | 6 +++++- > * 1 file changed, 5 insertions(+), 1 deletion(-) > * > *diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > *index 290f9e3..079760b 100644 > *--- a/kernel/sched/fair.c > *+++ b/kernel/sched/fair.c > *@@ -794,7 +794,11 @@ void post_init_entity_util_avg(struct task_struct *p) > * > * if (cap > 0) { > * if (cfs_rq->avg.util_avg != 0) { > *- sa->util_avg = cfs_rq->avg.util_avg * > se->load.weight; > *+ if (p->sched_class == &fair_sched_class) > *+ sa->util_avg = cfs_rq->avg.util_avg * > se_weight(se); > *+ else > *+ sa->util_avg = cfs_rq->avg.util_avg * > se->load.weight; > *+ > * sa->util_avg /= (cfs_rq->avg.load_avg + 1); > * > * if (sa->util_avg > cap) > * > --- > comment from Vincent Guittot <[email protected]>: > > > > According to the original code logic: > > cfs_rq->avg.util_avg > > sa->util_avg = -------------------- * se->load.weight > > cfs_rq->avg.load_avg > > this should have been scale_load_down(se->load.weight) from the beginning > > > but for fair_sched_class: > > se->load.weight = 1024 * sched_prio_to_weight[prio]; > > This is only true for 64bits platform otherwise scale_load and > scale_load_down are nop > > > cfs_rq->avg.util_avg > > so the -------------------- must be extremely small, the > > cfs_rq->avg.load_avg > > judgment condition "sa->util_avg < cap" could be established. > > It's not fair for those tasks who has smaller nice value. > > > > Signed-off-by: Xuewen Yan <[email protected]> > > --- > > kernel/sched/fair.c | 6 +++++- > > 1 file changed, 5 insertions(+), 1 deletion(-) > > > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > > index 290f9e3..079760b 100644 > > --- a/kernel/sched/fair.c > > +++ b/kernel/sched/fair.c > > @@ -794,7 +794,11 @@ void post_init_entity_util_avg(struct task_struct *p) > > > > if (cap > 0) { > > if (cfs_rq->avg.util_avg != 0) { > > We should now use cpu_util() instead of cfs_rq->avg.util_avg which > takes into account other classes > > > - sa->util_avg = cfs_rq->avg.util_avg * > > se->load.weight; > > + if (p->sched_class == &fair_sched_class) > > + sa->util_avg = cfs_rq->avg.util_avg * > > se_weight(se); > > + else > > + sa->util_avg = cfs_rq->avg.util_avg * > > se->load.weight; > > Why this else keeps using se->load.weight ? > > Either we uses sa->util_avg = cfs_rq->avg.util_avg * se_weight(se); > for all classes > > Or we want a different init value for other classes. But in this case > se->load.weight is meaningless and we should simply set them to 0 > although we could probably compute a value based on bandwidth for > deadline class. > > --- > kernel/sched/fair.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 290f9e3..c6186cc 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -794,7 +794,7 @@ void post_init_entity_util_avg(struct task_struct *p) > > if (cap > 0) { > if (cfs_rq->avg.util_avg != 0) { > - sa->util_avg = cfs_rq->avg.util_avg * se->load.weight; > + sa->util_avg = cfs_rq->avg.util_avg * se_weight(se);
Please refer to this MessageID: 20161208012722.GA4128@geo in lkml web site if you want. Just a notice and no matter here. My head do not work now. I can't remember more things that time.. > sa->util_avg /= (cfs_rq->avg.load_avg + 1); > > if (sa->util_avg > cap) > -- > 1.9.1 >
