Messages in this thread Patch in this message | | | From | Vincent Guittot <> | Date | Fri, 12 Nov 2021 17:05:41 +0100 | Subject | Re: [PATCH 1/2] sched/fair: skip newidle update stats |
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On Fri, 12 Nov 2021 at 15:55, Peter Zijlstra <peterz@infradead.org> wrote: > > > Subject: sched/fair: Reflow newidle_balance() > From: Peter Zijlstra <peterz@infradead.org> > Date: Fri Nov 12 15:46:08 CET 2021 > > The control flow in newidle_balance() is a little convoluted, attempt > simplification. > > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> > --- > kernel/sched/fair.c | 21 ++++++++------------- > 1 file changed, 8 insertions(+), 13 deletions(-) > > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -10858,10 +10858,10 @@ static inline void nohz_newidle_balance( > static int newidle_balance(struct rq *this_rq, struct rq_flags *rf) > { > unsigned long next_balance = jiffies + HZ; > + int pulled_task = 0, timeout = 0; > int this_cpu = this_rq->cpu; > u64 t0, t1, curr_cost = 0; > struct sched_domain *sd; > - int pulled_task = 0, early_stop = 0; > > update_misfit_status(NULL, this_rq); > > @@ -10889,17 +10889,9 @@ static int newidle_balance(struct rq *th > 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; > - } > - > goto out; > } > > @@ -10922,7 +10914,7 @@ static int newidle_balance(struct rq *th > update_next_balance(sd, &next_balance); > > if (this_rq->avg_idle < curr_cost + sd->max_newidle_lb_cost) { > - early_stop = 1; > + timeout = 1; > break; > } > > @@ -10967,6 +10959,11 @@ static int newidle_balance(struct rq *th > if (this_rq->nr_running != this_rq->cfs.h_nr_running) > pulled_task = -1; > > + if (pulled_task || timeout) > + goto out; > + > + nohz_newidle_balance(this_rq);
maybe
if (!pulled_task && !timeout) nohz_newidle_balance(this_rq);
> + > out: > /* Move the next balance forward */ > if (time_after(this_rq->next_balance, next_balance)) > @@ -10974,8 +10971,6 @@ static int newidle_balance(struct rq *th > > if (pulled_task) > this_rq->idle_stamp = 0; > - else if (!early_stop) > - nohz_newidle_balance(this_rq); > > return pulled_task; > }
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