From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: Re: [PATCH v9 05/10] cpuidle: Return nohz hint from cpuidle_select() Date: Fri, 06 Apr 2018 14:56:36 +0200 Message-ID: <34634950.bjF6TWOVDx@aspire.rjw.lan> References: <1736751.LdhZHb50jq@aspire.rjw.lan> <20180406024413.GB4400@lerouge> <6471749.luEdDuCiOl@aspire.rjw.lan> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Return-path: In-Reply-To: <6471749.luEdDuCiOl@aspire.rjw.lan> Sender: linux-kernel-owner@vger.kernel.org To: Frederic Weisbecker Cc: Linux PM , Peter Zijlstra , Frederic Weisbecker , Thomas Gleixner , Paul McKenney , Thomas Ilsche , Doug Smythies , Rik van Riel , Aubrey Li , Mike Galbraith , LKML , Len Brown List-Id: linux-pm@vger.kernel.org On Friday, April 6, 2018 10:11:04 AM CEST Rafael J. Wysocki wrote: > On Friday, April 6, 2018 4:44:14 AM CEST Frederic Weisbecker wrote: > > On Wed, Apr 04, 2018 at 10:39:50AM +0200, Rafael J. Wysocki wrote: > > > From: Rafael J. Wysocki > > > Index: linux-pm/kernel/time/tick-sched.c > > > =================================================================== > > > --- linux-pm.orig/kernel/time/tick-sched.c > > > +++ linux-pm/kernel/time/tick-sched.c > > > @@ -991,6 +991,20 @@ void tick_nohz_irq_exit(void) > > > } [cut] > So what about this? And moving the duplicated piece of got_idle_tick > manipulation on top of it? And appended is a patch to get rid of the code duplication (on top of the one below), for completeness. > --- > From: Frederic Weisbecker > Subject: [PATCH] nohz: Gather tick_sched booleans under a common flag field > > Optimize the space and leave plenty of room for further flags. > > Signed-off-by: Frederic Weisbecker > [ rjw: Do not use __this_cpu_read() to access tick_stopped and add > got_idle_tick to avoid overloading inidle ] > Signed-off-by: Rafael J. Wysocki > --- > kernel/time/tick-sched.c | 12 +++++++----- > kernel/time/tick-sched.h | 12 ++++++++---- > 2 files changed, 15 insertions(+), 9 deletions(-) > > Index: linux-pm/kernel/time/tick-sched.h > =================================================================== > --- linux-pm.orig/kernel/time/tick-sched.h > +++ linux-pm/kernel/time/tick-sched.h > @@ -41,19 +41,24 @@ enum tick_nohz_mode { > * @timer_expires: Anticipated timer expiration time (in case sched tick is stopped) > * @timer_expires_base: Base time clock monotonic for @timer_expires > * @do_timer_lst: CPU was the last one doing do_timer before going idle > + * @got_idle_tick: Tick timer function has run with @inidle set > */ > struct tick_sched { > struct hrtimer sched_timer; > unsigned long check_clocks; > enum tick_nohz_mode nohz_mode; > + > + unsigned int inidle : 1; > + unsigned int tick_stopped : 1; > + unsigned int idle_active : 1; > + unsigned int do_timer_last : 1; > + unsigned int got_idle_tick : 1; > + > ktime_t last_tick; > ktime_t next_tick; > - int inidle; > - int tick_stopped; > unsigned long idle_jiffies; > unsigned long idle_calls; > unsigned long idle_sleeps; > - int idle_active; > ktime_t idle_entrytime; > ktime_t idle_waketime; > ktime_t idle_exittime; > @@ -64,7 +69,6 @@ struct tick_sched { > u64 timer_expires_base; > u64 next_timer; > ktime_t idle_expires; > - int do_timer_last; > atomic_t tick_dep_mask; > }; > > Index: linux-pm/kernel/time/tick-sched.c > =================================================================== > --- linux-pm.orig/kernel/time/tick-sched.c > +++ linux-pm/kernel/time/tick-sched.c > @@ -465,7 +465,9 @@ __setup("nohz=", setup_tick_nohz); > > bool tick_nohz_tick_stopped(void) > { > - return __this_cpu_read(tick_cpu_sched.tick_stopped); > + struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); > + > + return ts->tick_stopped; > } > > bool tick_nohz_tick_stopped_cpu(int cpu) > @@ -1014,8 +1016,8 @@ bool tick_nohz_idle_got_tick(void) > { > struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); > > - if (ts->inidle > 1) { > - ts->inidle = 1; > + if (ts->got_idle_tick) { > + ts->got_idle_tick = 0; > return true; > } > return false; > @@ -1161,7 +1163,7 @@ static void tick_nohz_handler(struct clo > ktime_t now = ktime_get(); > > if (ts->inidle) > - ts->inidle = 2; > + ts->got_idle_tick = 1; > > dev->next_event = KTIME_MAX; > > @@ -1261,7 +1263,7 @@ static enum hrtimer_restart tick_sched_t > ktime_t now = ktime_get(); > > if (ts->inidle) > - ts->inidle = 2; > + ts->got_idle_tick = 1; > > tick_sched_do_timer(now); > --- From: Rafael J. Wysocki Subject: [PATCH] nohz: Avoid duplication of code related to got_idle_tick Move the code setting ts->got_idle_tick into tick_sched_do_timer() to avoid code duplication. No intentional changes in functionality. Suggested-by: Frederic Weisbecker Signed-off-by: Rafael J. Wysocki --- kernel/time/tick-sched.c | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-) Index: linux-pm/kernel/time/tick-sched.c =================================================================== --- linux-pm.orig/kernel/time/tick-sched.c +++ linux-pm/kernel/time/tick-sched.c @@ -113,8 +113,7 @@ static ktime_t tick_init_jiffy_update(vo return period; } - -static void tick_sched_do_timer(ktime_t now) +static void tick_sched_do_timer(struct tick_sched *ts, ktime_t now) { int cpu = smp_processor_id(); @@ -134,6 +133,9 @@ static void tick_sched_do_timer(ktime_t /* Check, if the jiffies need an update */ if (tick_do_timer_cpu == cpu) tick_do_update_jiffies64(now); + + if (ts->inidle) + ts->got_idle_tick = 1; } static void tick_sched_handle(struct tick_sched *ts, struct pt_regs *regs) @@ -1162,12 +1164,9 @@ static void tick_nohz_handler(struct clo struct pt_regs *regs = get_irq_regs(); ktime_t now = ktime_get(); - if (ts->inidle) - ts->got_idle_tick = 1; - dev->next_event = KTIME_MAX; - tick_sched_do_timer(now); + tick_sched_do_timer(ts, now); tick_sched_handle(ts, regs); /* No need to reprogram if we are running tickless */ @@ -1262,10 +1261,7 @@ static enum hrtimer_restart tick_sched_t struct pt_regs *regs = get_irq_regs(); ktime_t now = ktime_get(); - if (ts->inidle) - ts->got_idle_tick = 1; - - tick_sched_do_timer(now); + tick_sched_do_timer(ts, now); /* * Do not call, when we are not in irq context and have