From: "Rafael J. Wysocki" <rjw@rjwysocki.net> To: Peter Zijlstra <peterz@infradead.org>, Linux PM <linux-pm@vger.kernel.org> Cc: 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> Subject: [Correction][RFT][PATCH v7 3/8] sched: idle: Do not stop the tick before cpuidle_idle_call() Date: Tue, 20 Mar 2018 19:00:37 +0100 Message-ID: <8465308.mkr1foup4p@aspire.rjw.lan> (raw) In-Reply-To: <5325267.FN4F6lrTUU@aspire.rjw.lan> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Make cpuidle_idle_call() decide whether or not to stop the tick. First, the cpuidle_enter_s2idle() path deals with the tick (and with the entire timekeeping for that matter) by itself and it doesn't need the tick to be stopped beforehand. Second, to address the issue with short idle duration predictions by the idle governor after the tick has been stopped, it will be necessary to change the ordering of cpuidle_select() with respect to tick_nohz_idle_stop_tick(). To prepare for that, put a tick_nohz_idle_stop_tick() call in the same branch in which cpuidle_select() is called. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> --- The correct patch this time. --- kernel/sched/idle.c | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) Index: linux-pm/kernel/sched/idle.c =================================================================== --- linux-pm.orig/kernel/sched/idle.c +++ linux-pm/kernel/sched/idle.c @@ -146,13 +146,15 @@ static void cpuidle_idle_call(void) } /* - * Tell the RCU framework we are entering an idle section, - * so no more rcu read side critical sections and one more + * The RCU framework needs to be told that we are entering an idle + * section, so no more rcu read side critical sections and one more * step to the grace period */ - rcu_idle_enter(); if (cpuidle_not_available(drv, dev)) { + tick_nohz_idle_stop_tick(); + rcu_idle_enter(); + default_idle_call(); goto exit_idle; } @@ -169,16 +171,26 @@ static void cpuidle_idle_call(void) if (idle_should_enter_s2idle() || dev->use_deepest_state) { if (idle_should_enter_s2idle()) { + rcu_idle_enter(); + entered_state = cpuidle_enter_s2idle(drv, dev); if (entered_state > 0) { local_irq_enable(); goto exit_idle; } + + rcu_idle_exit(); } + tick_nohz_idle_stop_tick(); + rcu_idle_enter(); + next_state = cpuidle_find_deepest_state(drv, dev); call_cpuidle(drv, dev, next_state); } else { + tick_nohz_idle_stop_tick(); + rcu_idle_enter(); + /* * Ask the cpuidle framework to choose a convenient idle state. */ @@ -245,7 +257,6 @@ static void do_idle(void) tick_nohz_idle_restart_tick(); cpu_idle_poll(); } else { - tick_nohz_idle_stop_tick(); cpuidle_idle_call(); } arch_cpu_idle_exit();
next prev parent reply index Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-03-20 15:12 [RFT][PATCH v7 0/8] sched/cpuidle: Idle loop rework Rafael J. Wysocki 2018-03-20 15:13 ` [RFT][PATCH v7 1/8] time: tick-sched: Reorganize idle tick management code Rafael J. Wysocki 2018-03-20 15:15 ` [RFT][PATCH v7 2/8] sched: idle: Do not stop the tick upfront in the idle loop Rafael J. Wysocki 2018-03-20 15:15 ` [RFT][PATCH v7 3/8] " Rafael J. Wysocki 2018-03-20 18:00 ` Rafael J. Wysocki [this message] 2018-03-20 15:16 ` [RFT][PATCH v7 4/8] jiffies: Introduce USER_TICK_USEC and redefine TICK_USEC Rafael J. Wysocki 2018-03-20 15:45 ` [RFT][PATCH v7 5/8] cpuidle: Return nohz hint from cpuidle_select() Rafael J. Wysocki 2018-03-21 6:48 ` [RFT][PATCH v7.1 " Rafael J. Wysocki 2018-03-21 11:52 ` Rafael J. Wysocki 2018-03-21 13:03 ` [RFT][PATCH v7.2 " Rafael J. Wysocki 2018-03-21 14:36 ` [RFT][PATCH v7 " Rafael J. Wysocki 2018-03-21 17:59 ` Thomas Ilsche 2018-03-21 22:15 ` Rafael J. Wysocki 2018-03-22 13:18 ` Thomas Ilsche 2018-03-22 17:23 ` Rafael J. Wysocki 2018-03-22 6:24 ` Doug Smythies 2018-03-22 15:41 ` Doug Smythies 2018-03-22 17:21 ` Rafael J. Wysocki 2018-03-21 18:23 ` Doug Smythies 2018-03-22 17:40 ` [RFT][PATCH v7.3 " Rafael J. Wysocki 2018-03-28 9:14 ` Thomas Ilsche 2018-03-30 9:39 ` Rafael J. Wysocki 2018-04-10 15:22 ` Thomas Ilsche 2018-03-22 20:46 ` Doug Smythies 2018-03-20 15:45 ` [RFT][PATCH v7 6/8] sched: idle: Select idle state before stopping the tick Rafael J. Wysocki 2018-03-27 21:50 ` Thomas Ilsche 2018-03-27 22:10 ` Rafael J. Wysocki 2018-03-28 8:13 ` Rafael J. Wysocki 2018-03-28 8:38 ` Thomas Ilsche 2018-03-28 10:37 ` Rafael J. Wysocki 2018-03-28 10:56 ` Rafael J. Wysocki 2018-03-28 15:15 ` Thomas Ilsche 2018-03-28 20:41 ` Doug Smythies 2018-03-28 23:11 ` Rafael J. Wysocki 2018-03-20 15:46 ` [RFT][PATCH v7 7/8] cpuidle: menu: Refine idle state selection for running tick Rafael J. Wysocki 2018-03-20 15:47 ` [RFT][PATCH v7 8/8] cpuidle: menu: Avoid selecting shallow states with stopped tick Rafael J. Wysocki 2018-03-20 17:52 ` [RFT][PATCH v7 3/8] sched: idle: Do not stop the tick upfront in the idle loop Doug Smythies 2018-03-20 18:01 ` Rafael J. Wysocki 2018-03-21 12:31 ` [RFT][PATCH v7 0/8] sched/cpuidle: Idle loop rework Rik van Riel 2018-03-21 13:55 ` Rafael J. Wysocki 2018-03-21 14:53 ` Rik van Riel
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