From: Peter Zijlstra <peterz@infradead.org>
To: Suren Baghdasaryan <surenb@google.com>
Cc: "Johannes Weiner" <hannes@cmpxchg.org>,
"Ingo Molnar" <mingo@redhat.com>,
"Juri Lelli" <juri.lelli@redhat.com>,
"Vincent Guittot" <vincent.guittot@linaro.org>,
"Dietmar Eggemann" <dietmar.eggemann@arm.com>,
"Steven Rostedt" <rostedt@goodmis.org>,
"Benjamin Segall" <bsegall@google.com>,
"Mel Gorman" <mgorman@suse.de>,
"Daniel Bristot de Oliveira" <bristot@redhat.com>,
matthias.bgg@gmail.com, "Minchan Kim" <minchan@google.com>,
"Tim Murray" <timmurray@google.com>,
"YT Chang" <yt.chang@mediatek.com>,
"Wenju Xu (许文举)" <wenju.xu@mediatek.com>,
"Jonathan JMChen (陳家明)" <jonathan.jmchen@mediatek.com>,
LKML <linux-kernel@vger.kernel.org>,
linux-arm-kernel@lists.infradead.org,
linux-mediatek@lists.infradead.org,
kernel-team <kernel-team@android.com>,
"SH Chen" <show-hong.chen@mediatek.com>
Subject: Re: [PATCH v2 1/1] psi: stop relying on timer_pending for poll_work rescheduling
Date: Thu, 1 Jul 2021 18:12:00 +0200 [thread overview]
Message-ID: <YN3pUNgpBjn42f8s@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <CAJuCfpF=Ty4ruiKQQweVoF6Ojx8P8LxvUBxp1TmMFo2W1xNWfg@mail.gmail.com>
On Thu, Jul 01, 2021 at 09:09:25AM -0700, Suren Baghdasaryan wrote:
> On Thu, Jul 1, 2021 at 1:59 AM Peter Zijlstra <peterz@infradead.org> wrote:
> >
> > On Wed, Jun 30, 2021 at 01:51:51PM -0700, Suren Baghdasaryan wrote:
> > > + /* cmpxchg should be called even when !force to set poll_scheduled */
> > > + if (atomic_cmpxchg(&group->poll_scheduled, 0, 1) && !force)
> > > return;
> >
> > Why is that a cmpxchg() ?
>
> We want to set poll_scheduled and proceed with rescheduling the timer
> unless it's already scheduled, so cmpxchg helps us to make that
> decision atomically. Or did I misunderstand your question?
What's wrong with: atomic_xchg(&group->poll_scheduled, 1) ?
next prev parent reply other threads:[~2021-07-01 16:13 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-30 20:51 [PATCH v2 1/1] psi: stop relying on timer_pending for poll_work rescheduling Suren Baghdasaryan
2021-06-30 22:04 ` Johannes Weiner
2021-07-01 8:58 ` Peter Zijlstra
2021-07-01 16:09 ` Suren Baghdasaryan
2021-07-01 16:12 ` Peter Zijlstra [this message]
2021-07-01 16:28 ` Suren Baghdasaryan
2021-07-02 9:28 ` Peter Zijlstra
2021-07-02 15:49 ` Suren Baghdasaryan
2021-07-07 2:42 ` Suren Baghdasaryan
2021-07-01 16:39 ` Johannes Weiner
2021-07-01 17:46 ` Suren Baghdasaryan
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