Messages in this thread | | | Date | Fri, 12 Nov 2021 15:29:24 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH 1/2] sched/fair: skip newidle update stats |
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On Fri, Nov 12, 2021 at 10:58:56AM +0100, Vincent Guittot wrote: > In case we skip the newly idle LB entirely or we abort it because we are > going to exceed the avg_idle, we have to make sure to not start an update > of the blocked load when entering idle > > Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> > --- > kernel/sched/fair.c | 18 ++++++++++++++---- > 1 file changed, 14 insertions(+), 4 deletions(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 13950beb01a2..a162b0ec8963 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -10861,7 +10861,7 @@ static int newidle_balance(struct rq *this_rq, struct rq_flags *rf) > int this_cpu = this_rq->cpu; > u64 t0, t1, curr_cost = 0; > struct sched_domain *sd; > - int pulled_task = 0; > + int pulled_task = 0, early_stop = 0; > > update_misfit_status(NULL, this_rq); > > @@ -10898,8 +10898,16 @@ static int newidle_balance(struct rq *this_rq, struct rq_flags *rf) > if (!READ_ONCE(this_rq->rd->overload) || > (sd && this_rq->avg_idle < sd->max_newidle_lb_cost)) { > > - if (sd) > + if (sd) { > update_next_balance(sd, &next_balance); > + > + /* > + * We skip new idle LB because there is not enough > + * time before next wake up. Make sure that we will > + * not kick NOHZ_NEWILB_KICK > + */ > + early_stop = 1; > + } > rcu_read_unlock(); > > goto out; > @@ -10918,8 +10926,10 @@ static int newidle_balance(struct rq *this_rq, struct rq_flags *rf) > > update_next_balance(sd, &next_balance); > > - if (this_rq->avg_idle < curr_cost + sd->max_newidle_lb_cost) > + if (this_rq->avg_idle < curr_cost + sd->max_newidle_lb_cost) { > + early_stop = 1; > break; > + } > > if (sd->flags & SD_BALANCE_NEWIDLE) { > > @@ -10969,7 +10979,7 @@ static int newidle_balance(struct rq *this_rq, struct rq_flags *rf) > > if (pulled_task) > this_rq->idle_stamp = 0; > - else > + else if (!early_stop) > nohz_newidle_balance(this_rq); > > rq_repin_lock(this_rq, rf);
Urgh code flow is a mess... Let me see if I can fix some of that.
Anyway, does nohz_newidle_balance() want to loose it's ->avg_idle test with this on?
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