From: Peter Zijlstra <peterz@infradead.org>
To: Elliot Berman <quic_eberman@quicinc.com>
Cc: Ingo Molnar <mingo@redhat.com>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Pavel Machek <pavel@ucw.cz>, Thomas Gleixner <tglx@linutronix.de>,
kernel@quicinc.com, linux-arm-msm@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
Prakash Viswalingam <quic_prakashv@quicinc.com>
Subject: Re: [PATCH v2] freezer,sched: Use saved_state to reduce some spurious wakeups
Date: Mon, 4 Sep 2023 23:23:24 +0200 [thread overview]
Message-ID: <20230904212324.GA2568@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <20230830-avoid-spurious-freezer-wakeups-v2-1-8877245cdbdc@quicinc.com>
On Wed, Aug 30, 2023 at 10:42:39AM -0700, Elliot Berman wrote:
> Avoid the spurious wakeups by saving the state of TASK_FREEZABLE tasks.
> If the task was running before entering TASK_FROZEN state
> (__refrigerator()) or if the task received a wake up for the saved
> state, then the task is woken on thaw. saved_state from PREEMPT_RT locks
> can be re-used because freezer would not stomp on the rtlock wait flow:
> TASK_RTLOCK_WAIT isn't considered freezable.
You don't actually assert that anywhere I think, so the moment someone
makes that happen you crash and burn.
Also:
> -#ifdef CONFIG_PREEMPT_RT
> +#if IS_ENABLED(CONFIG_PREEMPT_RT) || IS_ENABLED(CONFIG_FREEZER)
That makes wakeup more horrible for everyone :/
next prev parent reply other threads:[~2023-09-04 21:23 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-30 17:42 [PATCH v2] freezer,sched: Use saved_state to reduce some spurious wakeups Elliot Berman
2023-09-04 21:23 ` Peter Zijlstra [this message]
2023-09-05 3:59 ` Elliot Berman
2023-09-07 9:46 ` Peter Zijlstra
2023-09-08 20:08 ` Elliot Berman
2023-09-08 22:08 ` Peter Zijlstra
2023-09-08 22:30 ` Elliot Berman
2023-09-08 22:48 ` Peter Zijlstra
2023-09-08 23:17 ` Elliot Berman
2023-09-09 9:29 ` Peter Zijlstra
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