From: "Rafael J. Wysocki" <rafael@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
Linux PM <linux-pm@vger.kernel.org>,
Frederic Weisbecker <fweisbec@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
Paul McKenney <paulmck@linux.vnet.ibm.com>,
Thomas Ilsche <thomas.ilsche@tu-dresden.de>,
Doug Smythies <dsmythies@telus.net>,
Rik van Riel <riel@surriel.com>,
Aubrey Li <aubrey.li@linux.intel.com>,
Mike Galbraith <mgalbraith@suse.de>,
LKML <linux-kernel@vger.kernel.org>,
Len Brown <len.brown@intel.com>
Subject: Re: [PATCH v9 10/10] cpuidle: menu: Avoid selecting shallow states with stopped tick
Date: Thu, 5 Apr 2018 15:49:32 +0200 [thread overview]
Message-ID: <CAJZ5v0h2c5RtUxwF2z3Gjy8O2RSBaD7wN3CxUXrg57jH57_xoA@mail.gmail.com> (raw)
In-Reply-To: <20180405124757.GQ4082@hirez.programming.kicks-ass.net>
On Thu, Apr 5, 2018 at 2:47 PM, Peter Zijlstra <peterz@infradead.org> wrote:
> On Wed, Apr 04, 2018 at 10:50:36AM +0200, Rafael J. Wysocki wrote:
>> + if (tick_nohz_tick_stopped()) {
>> + /*
>> + * If the tick is already stopped, the cost of possible short
>> + * idle duration misprediction is much higher, because the CPU
>> + * may be stuck in a shallow idle state for a long time as a
>> + * result of it. In that case say we might mispredict and try
>> + * to force the CPU into a state for which we would have stopped
>> + * the tick, unless the tick timer is going to expire really
>> + * soon anyway.
>
> Wait what; the tick was stopped, therefore it _cannot_ expire soon.
>
> *confused*
>
> Did you mean s/tick/a/ ?
Yeah, that should be "a timer".
next prev parent reply other threads:[~2018-04-05 13:49 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-04 8:32 [PATCH v9 00/10] sched/cpuidle: Idle loop rework Rafael J. Wysocki
2018-04-04 8:33 ` [PATCH v9 01/10] time: tick-sched: Reorganize idle tick management code Rafael J. Wysocki
2018-04-04 8:34 ` [PATCH v9 02/10] sched: idle: Do not stop the tick upfront in the idle loop Rafael J. Wysocki
2018-04-04 8:36 ` [PATCH v9 03/10] sched: idle: Do not stop the tick before cpuidle_idle_call() Rafael J. Wysocki
2018-04-04 8:38 ` [PATCH v9 04/10] jiffies: Introduce USER_TICK_USEC and redefine TICK_USEC Rafael J. Wysocki
2018-04-06 1:09 ` Frederic Weisbecker
2018-04-06 7:20 ` Rafael J. Wysocki
2018-04-04 8:39 ` [PATCH v9 05/10] cpuidle: Return nohz hint from cpuidle_select() Rafael J. Wysocki
2018-04-06 2:44 ` Frederic Weisbecker
2018-04-06 7:24 ` Rafael J. Wysocki
2018-04-06 14:19 ` Frederic Weisbecker
2018-04-06 7:58 ` Peter Zijlstra
2018-04-06 14:23 ` Frederic Weisbecker
2018-04-06 8:11 ` Rafael J. Wysocki
2018-04-06 12:56 ` Rafael J. Wysocki
2018-04-06 15:28 ` Frederic Weisbecker
2018-04-06 14:28 ` Frederic Weisbecker
2018-04-04 8:41 ` [PATCH v9 06/10] time: tick-sched: Split tick_nohz_stop_sched_tick() Rafael J. Wysocki
2018-04-07 2:36 ` Frederic Weisbecker
2018-04-07 16:36 ` Rafael J. Wysocki
2018-04-04 8:45 ` [PATCH v9 07/10] time: hrtimer: Introduce hrtimer_next_event_without() Rafael J. Wysocki
2018-04-07 14:46 ` Frederic Weisbecker
2018-04-08 8:20 ` Rafael J. Wysocki
2018-04-08 17:58 ` Frederic Weisbecker
2018-04-04 8:47 ` [PATCH v9 08/10] sched: idle: Select idle state before stopping the tick Rafael J. Wysocki
2018-04-09 2:41 ` Frederic Weisbecker
2018-04-04 8:49 ` [PATCH v9 09/10] cpuidle: menu: Refine idle state selection for running tick Rafael J. Wysocki
2018-04-05 12:27 ` Peter Zijlstra
2018-04-05 13:51 ` Rafael J. Wysocki
2018-04-05 12:32 ` Peter Zijlstra
2018-04-05 13:52 ` Rafael J. Wysocki
2018-04-04 8:50 ` [PATCH v9 10/10] cpuidle: menu: Avoid selecting shallow states with stopped tick Rafael J. Wysocki
2018-04-05 12:47 ` Peter Zijlstra
2018-04-05 13:49 ` Rafael J. Wysocki [this message]
2018-04-05 14:11 ` Peter Zijlstra
2018-04-05 14:13 ` Peter Zijlstra
2018-04-05 14:29 ` Rafael J. Wysocki
2018-04-08 16:32 ` [PATCH v9 00/10] sched/cpuidle: Idle loop rework Rafael J. Wysocki
2018-04-09 15:58 ` Thomas Ilsche
2018-04-10 7:03 ` Rafael J. Wysocki
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