| Message ID | 6471749.luEdDuCiOl@aspire.rjw.lan (mailing list archive) |
|---|---|
| State | Mainlined |
| Delegated to: | Rafael Wysocki |
| Headers | show |
On Fri, Apr 06, 2018 at 10:11:04AM +0200, 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 <rafael.j.wysocki@intel.com> > > > 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) > > > } > > > > > > /** > > > + * tick_nohz_idle_got_tick - Check whether or not the tick handler has run > > > + */ > > > +bool tick_nohz_idle_got_tick(void) > > > +{ > > > + struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); > > > + > > > + if (ts->inidle > 1) { > > > + ts->inidle = 1; > > > + return true; > > > + } > > > + return false; > > > +} > > > + > > > +/** > > > * tick_nohz_get_sleep_length - return the length of the current sleep > > > * > > > * Called from power state control code with interrupts disabled > > > @@ -1101,6 +1115,9 @@ static void tick_nohz_handler(struct clo > > > struct pt_regs *regs = get_irq_regs(); > > > ktime_t now = ktime_get(); > > > > > > + if (ts->inidle) > > > + ts->inidle = 2; > > > + > > > > You can move that to tick_sched_do_timer() to avoid code duplication. > > > > Also these constants are very opaque. And even with proper symbols it wouldn't look > > right to extend ts->inidle that way. > > > > Perhaps you should add a field such as ts->got_idle_tick under the boolean fields > > after the below patch: > > > > -- > > From c7b2ca5a4c512517ddfeb9f922d5999f82542ced Mon Sep 17 00:00:00 2001 > > From: Frederic Weisbecker <frederic@kernel.org> > > Date: Fri, 6 Apr 2018 04:32:37 +0200 > > Subject: [PATCH] nohz: Gather tick_sched booleans under a common flag field > > > > This optimize the space and leave plenty of room for further flags. > > > > Signed-off-by: Frederic Weisbecker <frederic@kernel.org> > > --- > > kernel/time/tick-sched.h | 10 ++++++---- > > 1 file changed, 6 insertions(+), 4 deletions(-) > > > > diff --git a/kernel/time/tick-sched.h b/kernel/time/tick-sched.h > > index 954b43d..38f24dc 100644 > > --- a/kernel/time/tick-sched.h > > +++ b/kernel/time/tick-sched.h > > @@ -45,14 +45,17 @@ 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; > > This particular change breaks build, because tick_stopped is > accessed via __this_cpu_read() in tick_nohz_tick_stopped(). Oops... > > > + unsigned int idle_active : 1; > > + unsigned int do_timer_last : 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; > > @@ -62,7 +65,6 @@ struct tick_sched { > > unsigned long last_jiffies; > > u64 next_timer; > > ktime_t idle_expires; > > - int do_timer_last; > > atomic_t tick_dep_mask; > > }; > > > > > > So what about this? And moving the duplicated piece of got_idle_tick > manipulation on top of it? > > --- > From: Frederic Weisbecker <frederic@kernel.org> > 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 <frederic@kernel.org> > [ 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 <rafael.j.wysocki@intel.com> Yeah looks good, thanks!
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);