On Mon, 17 Dec 2018 at 17:59, Valentin Schneider <valentin.schnei...@arm.com> wrote: > > Hi Vincent, > > On 14/12/2018 16:01, Vincent Guittot wrote: > > newly idle load balance is not always triggered when a cpu becomes idle. > > This prevent the scheduler to get a chance to migrate task for asym packing. > > Enable active migration because of asym packing during idle load balance > > too. > > > > Signed-off-by: Vincent Guittot <vincent.guit...@linaro.org> > > --- > > 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 c215f7a..9591e7a 100644 > > --- a/kernel/sched/fair.c > > +++ b/kernel/sched/fair.c > > @@ -8861,7 +8861,7 @@ static int need_active_balance(struct lb_env *env) > > { > > struct sched_domain *sd = env->sd; > > > > - if (env->idle == CPU_NEWLY_IDLE) { > > + if (env->idle != CPU_NOT_IDLE) { > > > > /* > > * ASYM_PACKING needs to force migrate tasks from busy but > > > > That change looks fine. However, you're mentioning newidle load_balance() > not being triggered - you'd want to set root_domain->overload for any > newidle pull to happen, probably with something like this:
It's not needed in this case because the dst cpu is already the target cpu and the migration will happen during this idle load balance. Setting root_domain->overload is useful only if you want another cpu to pull the task during another coming load_balance (newly or normal idle ones) which is not the case here. > > -----8<----- > @@ -8398,6 +8408,9 @@ static inline void update_sd_lb_stats(struct lb_env > *env, struct sd_lb_stats *sd > sg = sg->next; > } while (sg != env->sd->groups); > > + if (check_asym_packing(env, sds)) > + sg_status |= SG_OVERLOAD; > + > #ifdef CONFIG_NO_HZ_COMMON > if ((env->flags & LBF_NOHZ_AGAIN) && > cpumask_subset(nohz.idle_cpus_mask, sched_domain_span(env->sd))) { > ----->8----- > > It's similar to what is done for misfit, although that's yet another > 'twisted' use of that flag which we might want to rename (I suggested > something like 'need_idle_balance' a while back but it wasn't really > popular).