From: Dietmar Eggemann <dietmar.eggemann@arm.com>
To: Valentin Schneider <valentin.schneider@arm.com>,
linux-kernel@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
Vincent Guittot <vincent.guittot@linaro.org>
Subject: Re: [PATCH v2 2/2] sched/fair: Trigger nohz.next_balance updates when a CPU goes NOHZ-idle
Date: Tue, 20 Jul 2021 12:47:21 +0200 [thread overview]
Message-ID: <dce1c131-d52d-4eec-276b-3a2eeefabb3d@arm.com> (raw)
In-Reply-To: <878s22mfnn.mognet@arm.com>
On 19/07/2021 18:28, Valentin Schneider wrote:
> On 19/07/21 17:24, Dietmar Eggemann wrote:
>> On 19/07/2021 12:31, Valentin Schneider wrote:
[...]
>>> * Ensures that if we miss the CPU, we must see the has_blocked
>>> @@ -10531,6 +10540,8 @@ static void _nohz_idle_balance(struct rq *this_rq, unsigned int flags,
>>> if (need_resched()) {
>>> if (flags & NOHZ_STATS_KICK)
>>> has_blocked_load = true;
>>
>> This looks weird now? 'has_blocked_load = true' vs
>> 'WRITE_ONCE(nohz.needs_update, 1)'.
>>
>
> Well, has_blocked_load lets us factorize the nohz.has_blocked write
> (one is needed either when aborting or at the tail of the cpumask
> iteration), whereas there is just a single write for nohz.needs_update
> (when aborting).
You're right. Looks good then.
[...]
prev parent reply other threads:[~2021-07-20 11:01 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-19 10:31 [PATCH v2 0/2] sched/fair: nohz.next_balance vs newly-idle CPUs Valentin Schneider
2021-07-19 10:31 ` [PATCH v2 1/2] sched/fair: Add NOHZ balancer flag for nohz.next_balance updates Valentin Schneider
2021-08-10 13:33 ` Vincent Guittot
2021-07-19 10:31 ` [PATCH v2 2/2] sched/fair: Trigger nohz.next_balance updates when a CPU goes NOHZ-idle Valentin Schneider
2021-07-19 15:24 ` Dietmar Eggemann
2021-07-19 16:28 ` Valentin Schneider
2021-07-20 10:47 ` Dietmar Eggemann [this message]
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