From: Oleg Nesterov <oleg@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: rjw@rjwysocki.net, mingo@kernel.org, vincent.guittot@linaro.org,
dietmar.eggemann@arm.com, rostedt@goodmis.org, mgorman@suse.de,
Will Deacon <will@kernel.org>, Tejun Heo <tj@kernel.org>,
linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org
Subject: Re: [PATCH] freezer,sched: Rewrite core freezer logic
Date: Tue, 15 Jun 2021 17:45:39 +0200 [thread overview]
Message-ID: <20210615154539.GA30333@redhat.com> (raw)
In-Reply-To: <20210614183801.GE68749@worktop.programming.kicks-ass.net>
On 06/14, Peter Zijlstra wrote:
>
> One more thing; if I add additional state bits to preserve
> __TASK_{TRACED,STOPPED}, then I need to figure out at thaw time if we've
> missed a wakeup or not.
>
> Do we have sufficient state for that? If so, don't we then also not have
> sufficient state to tell if a task should've been TRACED/STOPPED in the
> first place?
Not sure I understand you, probably not, but I think the answer is "no" ;)
But this reminds me... can't we implement selective wakeups? So that if a
task T sleeps in state = STOPPED | FROZEN, then ttwu(T, FROZEN) won't wake
it up, it will only clear FROZEN from T->state. Similarly, ttwu(T, STOPPED)
will leave this task with state == FROZEN.
See also
https://lore.kernel.org/lkml/20131112162136.GA29065@redhat.com/
https://lore.kernel.org/lkml/20131113170724.GA17739@redhat.com/
just to remind you that we already discussed TASK_FROZEN a little bit almost
10 years ago ;)
What has been shall be, and what has been done is what will be done, and
there is nothing new under the sun.
Oleg.
next prev parent reply other threads:[~2021-06-15 15:45 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-11 8:45 [PATCH] freezer,sched: Rewrite core freezer logic Peter Zijlstra
2021-06-11 8:46 ` Peter Zijlstra
2021-06-11 13:58 ` Rafael J. Wysocki
2021-06-14 15:42 ` Oleg Nesterov
2021-06-14 16:12 ` Peter Zijlstra
2021-06-14 16:54 ` Oleg Nesterov
2021-06-14 18:38 ` Peter Zijlstra
2021-06-15 15:45 ` Oleg Nesterov [this message]
2021-06-15 21:35 ` Peter Zijlstra
2021-06-15 21:50 ` Peter Zijlstra
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