Message ID | 1523531671-27491-7-git-send-email-ulf.hansson@linaro.org (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
On Thu, Apr 12, 2018 at 1:14 PM, Ulf Hansson <ulf.hansson@linaro.org> wrote: > From: Lina Iyer <lina.iyer@linaro.org> > > Knowing the sleep duration of CPUs, is known to be needed while selecting > the most energy efficient idle state for a CPU or a group of CPUs. > > However, to be able to compute the sleep duration, we need to know at what > time the next expected wakeup is for the CPU. Therefore, let's export this > information via a new function, tick_nohz_get_next_wakeup(). Following > changes make use of it. > > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Daniel Lezcano <daniel.lezcano@linaro.org> > Cc: Lina Iyer <ilina@codeaurora.org> > Cc: Frederic Weisbecker <fweisbec@gmail.com> > Cc: Ingo Molnar <mingo@kernel.org> > Signed-off-by: Lina Iyer <lina.iyer@linaro.org> > Co-developed-by: Ulf Hansson <ulf.hansson@linaro.org> > Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> > --- > include/linux/tick.h | 10 ++++++++++ > kernel/time/tick-sched.c | 11 +++++++++++ > 2 files changed, 21 insertions(+) > > diff --git a/include/linux/tick.h b/include/linux/tick.h > index 389aa25..d341811 100644 > --- a/include/linux/tick.h > +++ b/include/linux/tick.h > @@ -125,6 +125,7 @@ extern bool tick_nohz_idle_got_tick(void); > extern ktime_t tick_nohz_get_sleep_length(ktime_t *delta_next); > extern unsigned long tick_nohz_get_idle_calls(void); > extern unsigned long tick_nohz_get_idle_calls_cpu(int cpu); > +extern ktime_t tick_nohz_get_next_wakeup(int cpu); > extern u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time); > extern u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time); > > @@ -151,6 +152,15 @@ static inline ktime_t tick_nohz_get_sleep_length(ktime_t *delta_next) > *delta_next = TICK_NSEC; > return *delta_next; > } > + > +static inline ktime_t tick_nohz_get_next_wakeup(int cpu) > +{ > + ktime_t t; > + > + /* Next wake up is the tick period, assume it starts now */ > + return ktime_add(tick_nohz_get_sleep_length(&t), ktime_get()); > +} Well, given that tick_nohz_get_sleep_length() is just the above in this case, wouldn't it be simpler to return ktime_add(ktime_get(), TICK_NSEC) from here? > + > static inline u64 get_cpu_idle_time_us(int cpu, u64 *unused) { return -1; } > static inline u64 get_cpu_iowait_time_us(int cpu, u64 *unused) { return -1; } > > diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c > index 646645e..08db7f3 100644 > --- a/kernel/time/tick-sched.c > +++ b/kernel/time/tick-sched.c > @@ -1098,6 +1098,17 @@ unsigned long tick_nohz_get_idle_calls(void) > return ts->idle_calls; > } > > +/** > + * tick_nohz_get_next_wakeup - return the next wake up of the CPU > + */ > +ktime_t tick_nohz_get_next_wakeup(int cpu) > +{ > + struct clock_event_device *dev = > + per_cpu(tick_cpu_device.evtdev, cpu); I would avoid breaking the line, honestly. If you really really want to avoid going above the 80 chars line length limit, why don't you do struct clock_event_device *dev; dev = per_cpu(tick_cpu_device.evtdev, cpu); > + > + return dev->next_event; > +} > + > static void tick_nohz_account_idle_ticks(struct tick_sched *ts) > { > #ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE > --
On 13 April 2018 at 10:47, Rafael J. Wysocki <rafael@kernel.org> wrote: > On Thu, Apr 12, 2018 at 1:14 PM, Ulf Hansson <ulf.hansson@linaro.org> wrote: >> From: Lina Iyer <lina.iyer@linaro.org> >> >> Knowing the sleep duration of CPUs, is known to be needed while selecting >> the most energy efficient idle state for a CPU or a group of CPUs. >> >> However, to be able to compute the sleep duration, we need to know at what >> time the next expected wakeup is for the CPU. Therefore, let's export this >> information via a new function, tick_nohz_get_next_wakeup(). Following >> changes make use of it. >> >> Cc: Thomas Gleixner <tglx@linutronix.de> >> Cc: Daniel Lezcano <daniel.lezcano@linaro.org> >> Cc: Lina Iyer <ilina@codeaurora.org> >> Cc: Frederic Weisbecker <fweisbec@gmail.com> >> Cc: Ingo Molnar <mingo@kernel.org> >> Signed-off-by: Lina Iyer <lina.iyer@linaro.org> >> Co-developed-by: Ulf Hansson <ulf.hansson@linaro.org> >> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> >> --- >> include/linux/tick.h | 10 ++++++++++ >> kernel/time/tick-sched.c | 11 +++++++++++ >> 2 files changed, 21 insertions(+) >> >> diff --git a/include/linux/tick.h b/include/linux/tick.h >> index 389aa25..d341811 100644 >> --- a/include/linux/tick.h >> +++ b/include/linux/tick.h >> @@ -125,6 +125,7 @@ extern bool tick_nohz_idle_got_tick(void); >> extern ktime_t tick_nohz_get_sleep_length(ktime_t *delta_next); >> extern unsigned long tick_nohz_get_idle_calls(void); >> extern unsigned long tick_nohz_get_idle_calls_cpu(int cpu); >> +extern ktime_t tick_nohz_get_next_wakeup(int cpu); >> extern u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time); >> extern u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time); >> >> @@ -151,6 +152,15 @@ static inline ktime_t tick_nohz_get_sleep_length(ktime_t *delta_next) >> *delta_next = TICK_NSEC; >> return *delta_next; >> } >> + >> +static inline ktime_t tick_nohz_get_next_wakeup(int cpu) >> +{ >> + ktime_t t; >> + >> + /* Next wake up is the tick period, assume it starts now */ >> + return ktime_add(tick_nohz_get_sleep_length(&t), ktime_get()); >> +} > > Well, given that tick_nohz_get_sleep_length() is just the above in > this case, wouldn't it be simpler to return ktime_add(ktime_get(), > TICK_NSEC) from here? Yes! > >> + >> static inline u64 get_cpu_idle_time_us(int cpu, u64 *unused) { return -1; } >> static inline u64 get_cpu_iowait_time_us(int cpu, u64 *unused) { return -1; } >> >> diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c >> index 646645e..08db7f3 100644 >> --- a/kernel/time/tick-sched.c >> +++ b/kernel/time/tick-sched.c >> @@ -1098,6 +1098,17 @@ unsigned long tick_nohz_get_idle_calls(void) >> return ts->idle_calls; >> } >> >> +/** >> + * tick_nohz_get_next_wakeup - return the next wake up of the CPU >> + */ >> +ktime_t tick_nohz_get_next_wakeup(int cpu) >> +{ >> + struct clock_event_device *dev = >> + per_cpu(tick_cpu_device.evtdev, cpu); > > I would avoid breaking the line, honestly. Alright, I have no problem with that. [,,,] Thanks for reviewing! Kind regards Uffe
diff --git a/include/linux/tick.h b/include/linux/tick.h index 389aa25..d341811 100644 --- a/include/linux/tick.h +++ b/include/linux/tick.h @@ -125,6 +125,7 @@ extern bool tick_nohz_idle_got_tick(void); extern ktime_t tick_nohz_get_sleep_length(ktime_t *delta_next); extern unsigned long tick_nohz_get_idle_calls(void); extern unsigned long tick_nohz_get_idle_calls_cpu(int cpu); +extern ktime_t tick_nohz_get_next_wakeup(int cpu); extern u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time); extern u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time); @@ -151,6 +152,15 @@ static inline ktime_t tick_nohz_get_sleep_length(ktime_t *delta_next) *delta_next = TICK_NSEC; return *delta_next; } + +static inline ktime_t tick_nohz_get_next_wakeup(int cpu) +{ + ktime_t t; + + /* Next wake up is the tick period, assume it starts now */ + return ktime_add(tick_nohz_get_sleep_length(&t), ktime_get()); +} + static inline u64 get_cpu_idle_time_us(int cpu, u64 *unused) { return -1; } static inline u64 get_cpu_iowait_time_us(int cpu, u64 *unused) { return -1; } diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 646645e..08db7f3 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -1098,6 +1098,17 @@ unsigned long tick_nohz_get_idle_calls(void) return ts->idle_calls; } +/** + * tick_nohz_get_next_wakeup - return the next wake up of the CPU + */ +ktime_t tick_nohz_get_next_wakeup(int cpu) +{ + struct clock_event_device *dev = + per_cpu(tick_cpu_device.evtdev, cpu); + + return dev->next_event; +} + static void tick_nohz_account_idle_ticks(struct tick_sched *ts) { #ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE