From: Vincent Guittot <vincent.guittot@linaro.org>
To: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Juri Lelli <juri.lelli@redhat.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
Frederic Weisbecker <fweisbec@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
Daniel Bristot de Oliveira <bristot@redhat.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
Joel Fernandes <joel@joelfernandes.org>,
Qais Yousef <qais.yousef@arm.com>
Subject: Re: [PATCH 2/6] sched/fair: remove unused parameter of update_nohz_stats
Date: Tue, 9 Feb 2021 18:38:26 +0100 [thread overview]
Message-ID: <CAKfTPtBCyjt+T33uc-p40fyvY3LU8FkAswifngGxaBFFgdM=Tg@mail.gmail.com> (raw)
In-Reply-To: <a5083b2f-31b7-f23d-092b-6442c01ef23a@arm.com>
On Tue, 9 Feb 2021 at 14:45, Dietmar Eggemann <dietmar.eggemann@arm.com> wrote:
>
> On 05/02/2021 12:48, Vincent Guittot wrote:
> > idle load balance is the only user of update_nohz_stats and doesn't use
> > force parameter. Remove it
>
> Wasn't the 'force=true' from ilb eclipsing the jiffy resolution rate
> limiting '!time_after(jiffies, rq->last_blocked_load_update_tick)' of
> update_blocked_averages()?
>
> So IMHO this has the (maybe intended) side effect that (formerly forced
> updates) are now rate limited on one jiffy resolution too.
Calls to _nohz_idle_balance were already rate limited by load balance
interval and nohz.next_blocked.
This tick rate limit has been originally added for newidle_balance
case but there were some corner cases for _nohz_idle_balance that
could benefit of this too
>
> >
> > Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
> > ---
> > kernel/sched/fair.c | 6 +++---
> > 1 file changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> > index bfe1e235fe01..60b8c1c68ab9 100644
> > --- a/kernel/sched/fair.c
> > +++ b/kernel/sched/fair.c
> > @@ -8352,7 +8352,7 @@ group_type group_classify(unsigned int imbalance_pct,
> > return group_has_spare;
> > }
> >
> > -static bool update_nohz_stats(struct rq *rq, bool force)
> > +static bool update_nohz_stats(struct rq *rq)
> > {
> > #ifdef CONFIG_NO_HZ_COMMON
> > unsigned int cpu = rq->cpu;
> > @@ -8363,7 +8363,7 @@ static bool update_nohz_stats(struct rq *rq, bool force)
> > if (!cpumask_test_cpu(cpu, nohz.idle_cpus_mask))
> > return false;
> >
> > - if (!force && !time_after(jiffies, rq->last_blocked_load_update_tick))
> > + if (!time_after(jiffies, rq->last_blocked_load_update_tick))
> > return true;
> >
> > update_blocked_averages(cpu);
> > @@ -10404,7 +10404,7 @@ static bool _nohz_idle_balance(struct rq *this_rq, unsigned int flags,
> >
> > rq = cpu_rq(balance_cpu);
> >
> > - has_blocked_load |= update_nohz_stats(rq, true);
> > + has_blocked_load |= update_nohz_stats(rq);
> >
> > /*
> > * If time for next balance is due,
> >
>
next prev parent reply other threads:[~2021-02-09 17:40 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-05 11:48 [PATCH 0/6] move update blocked load outside newidle_balance Vincent Guittot
2021-02-05 11:48 ` [PATCH 1/6] sched/fair: remove update of blocked load from newidle_balance Vincent Guittot
2021-02-09 13:09 ` Valentin Schneider
2021-02-09 13:20 ` Vincent Guittot
2021-02-09 13:44 ` Dietmar Eggemann
2021-02-05 11:48 ` [PATCH 2/6] sched/fair: remove unused parameter of update_nohz_stats Vincent Guittot
2021-02-09 13:45 ` Dietmar Eggemann
2021-02-09 17:38 ` Vincent Guittot [this message]
2021-02-05 11:48 ` [PATCH 3/6] sched/fair: merge for each idle cpu loop of ILB Vincent Guittot
2021-02-09 13:09 ` Valentin Schneider
2021-02-05 11:48 ` [PATCH 4/6] sched/fair: reorder newidle_balance pulled_task test Vincent Guittot
2021-02-09 13:46 ` Dietmar Eggemann
2021-02-05 11:48 ` [RFC PATCH 5/6] sched/fair: trigger the update of blocked load on newly idle cpu Vincent Guittot
2021-02-09 13:09 ` Valentin Schneider
2021-02-09 13:57 ` Vincent Guittot
2021-02-09 17:25 ` Valentin Schneider
2021-02-09 13:47 ` Dietmar Eggemann
2021-02-09 14:22 ` Vincent Guittot
2021-02-05 11:48 ` [PATCH 6/6] sched/fair: reduce the window for duplicated update Vincent Guittot
2021-02-05 16:13 ` [PATCH 6/6 v2] " Vincent Guittot
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