From: Peter Zijlstra <peterz@infradead.org>
To: Qais Yousef <qais.yousef@arm.com>
Cc: valentin.schneider@arm.com, tglx@linutronix.de, mingo@kernel.org,
bigeasy@linutronix.de, swood@redhat.com, juri.lelli@redhat.com,
vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
bristot@redhat.com, vincent.donnefort@arm.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/3] cpumask: Introduce DYING mask
Date: Mon, 12 Apr 2021 12:55:14 +0200 [thread overview]
Message-ID: <YHQnEgXFi3YAFvIP@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20210321193037.7o3mqcmwjthbos7n@e107158-lin>
On Sun, Mar 21, 2021 at 07:30:37PM +0000, Qais Yousef wrote:
> On 03/10/21 15:53, Peter Zijlstra wrote:
> > --- a/kernel/cpu.c
> > +++ b/kernel/cpu.c
> > @@ -160,6 +160,9 @@ static int cpuhp_invoke_callback(unsigne
> > int (*cb)(unsigned int cpu);
> > int ret, cnt;
> >
> > + if (bringup != !cpu_dying(cpu))
>
> nit: this condition is hard to read
>
> > + set_cpu_dying(cpu, !bringup);
How's:
if (cpu_dying(cpu) != !bringup)
set_cpu_dying(cpu, !bringup);
> since cpu_dying() will do cpumask_test_cpu(), are we saving much if we
> unconditionally call set_cpu_dying(cpu, !bringup) which performs
> cpumask_{set, clear}_cpu()?
This is hotplug, it's all slow, endlessly rewriting that bit shouldn't
be a problem I suppose.
next prev parent reply other threads:[~2021-04-12 10:56 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-10 14:52 [PATCH 0/3] sched: Fix remaining balance_push vs hotplug hole Peter Zijlstra
2021-03-10 14:52 ` [PATCH 1/3] cpumask: Make cpu_{online,possible,present,active}() inline Peter Zijlstra
2021-04-16 15:53 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-03-10 14:53 ` [PATCH 2/3] cpumask: Introduce DYING mask Peter Zijlstra
2021-03-21 19:30 ` Qais Yousef
2021-03-22 15:07 ` Steven Rostedt
2021-04-12 10:55 ` Peter Zijlstra [this message]
2021-04-12 11:16 ` Qais Yousef
2021-04-16 15:53 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-03-10 14:53 ` [PATCH 3/3] sched: Use cpu_dying() to fix balance_push vs hotplug-rollback Peter Zijlstra
2021-03-11 15:13 ` Valentin Schneider
2021-03-11 16:42 ` Peter Zijlstra
2021-04-12 12:03 ` Peter Zijlstra
2021-04-12 17:22 ` Valentin Schneider
2021-04-13 6:51 ` Peter Zijlstra
2021-04-15 8:59 ` Peter Zijlstra
2021-04-15 14:32 ` Valentin Schneider
2021-04-15 15:29 ` Peter Zijlstra
2021-04-15 15:34 ` Valentin Schneider
2021-04-19 10:56 ` Vincent Donnefort
2021-04-20 9:46 ` Vincent Donnefort
2021-04-20 14:20 ` Peter Zijlstra
2021-04-20 14:39 ` Peter Zijlstra
2021-04-20 14:58 ` Peter Zijlstra
2021-04-20 16:53 ` Vincent Donnefort
2021-04-20 18:07 ` Peter Zijlstra
2021-04-21 9:32 ` Valentin Schneider
2021-04-22 7:36 ` [tip: sched/core] cpumask/hotplug: Fix cpu_dying() state tracking tip-bot2 for Peter Zijlstra
2021-04-16 15:53 ` [tip: sched/core] sched: Use cpu_dying() to fix balance_push vs hotplug-rollback tip-bot2 for Peter Zijlstra
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