From: Vincent Guittot <vincent.guittot@linaro.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Brendan Jackman <brendan.jackman@arm.com>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Ingo Molnar <mingo@kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@redhat.com>,
Morten Rasmussen <morten.rasmussen@arm.com>
Subject: Re: [PATCH v2 1/2] sched: force update of blocked load of idle cpus
Date: Thu, 21 Dec 2017 11:01:15 +0100 [thread overview]
Message-ID: <CAKfTPtBt300QnodhodrzbN5M0Ka8TqjC5G6a_rAVOUH43_1yYA@mail.gmail.com> (raw)
In-Reply-To: <CAKfTPtC0Seb3MDDSv-ZASLUfvrTkZta_jSDR9DVM4QMW_0ohPg@mail.gmail.com>
On 20 December 2017 at 15:27, Vincent Guittot
<vincent.guittot@linaro.org> wrote:
> On 20 December 2017 at 15:09, Peter Zijlstra <peterz@infradead.org> wrote:
>> On Fri, Dec 01, 2017 at 06:01:56PM +0000, Brendan Jackman wrote:
>>
>>> @@ -9210,7 +9256,15 @@ static void nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle)
>>> cpu_load_update_idle(rq);
>>> rq_unlock_irq(rq, &rf);
>>>
>>> - rebalance_domains(rq, CPU_IDLE);
>>> + update_blocked_averages(balance_cpu);
>>> + /*
>>> + * This idle load balance softirq may have been
>>> + * triggered only to update the blocked load and shares
>>> + * of idle CPUs (which we have just done for
>>> + * balance_cpu). In that case skip the actual balance.
>>> + */
>>> + if (!in_nohz_stats_kick(this_cpu))
>>> + rebalance_domains(rq, idle);
>>> }
>>>
>>> if (time_after(next_balance, rq->next_balance)) {
>>
>>> @@ -9336,7 +9396,12 @@ static __latent_entropy void run_rebalance_domains(struct softirq_action *h)
>>> * and abort nohz_idle_balance altogether if we pull some load.
>>> */
>>> nohz_idle_balance(this_rq, idle);
>>> - rebalance_domains(this_rq, idle);
>>> + update_blocked_averages(this_rq->cpu);
>>> + if (!in_nohz_stats_kick(this_rq->cpu))
>>> + rebalance_domains(this_rq, idle);
>>> +#ifdef CONFIG_NO_HZ_COMMON
>>> + clear_bit(NOHZ_STATS_KICK, nohz_flags(this_rq->cpu));
>>> +#endif
>>> }
>>>
>>> /*
>>
>> You're doing the same thing to both (all) callsites of
>> rebalance_domains(), does that not suggest doing it inside and leaving
>> update_blocked_averages() where it is?
>
> The goal of moving update_blocked_averages() outside rebalance_domains
> is to not add a new parameter or use a special cpu_idle_type value in
> rebalance_domains parameters in order to abort the rebalance sequence
> just after updating blocked load
Peter,
Is the reason above reasonable or you prefer update_blocked_averages
to stay in rebalance_domains ?
>
>>
>>
next prev parent reply other threads:[~2017-12-21 10:01 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-01 18:01 [PATCH v2 0/2] sched/fair: remote load updates for idle CPUs Brendan Jackman
2017-12-01 18:01 ` [PATCH v2 1/2] sched: force update of blocked load of idle cpus Brendan Jackman
2017-12-20 14:03 ` Peter Zijlstra
2017-12-20 14:23 ` Vincent Guittot
2017-12-20 15:01 ` Peter Zijlstra
2017-12-20 15:05 ` Peter Zijlstra
2017-12-21 7:59 ` Vincent Guittot
2017-12-20 14:09 ` Peter Zijlstra
2017-12-20 14:27 ` Vincent Guittot
2017-12-21 10:01 ` Vincent Guittot [this message]
2017-12-01 18:01 ` [PATCH v2 2/2] sched/fair: Update blocked load from newly idle balance Brendan Jackman
2017-12-20 14:22 ` Peter Zijlstra
2017-12-21 9:19 ` Dietmar Eggemann
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