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| author | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2018-04-05 19:12:34 +0200 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2018-04-09 11:54:56 +0200 |
| commit | 296bb1e51a4838a6488ec5ce676607093482ecbc (patch) | |
| tree | 15bb67b6593378aa3cc3b60e8bf754278f7c53aa /kernel/time/tick-sched.c | |
| parent | 554c8aa8ecade210d58a252173bb8f2106552a44 (diff) | |
| download | linux-296bb1e51a4838a6488ec5ce676607093482ecbc.tar.bz2 | |
cpuidle: menu: Refine idle state selection for running tick
If the tick isn't stopped, the target residency of the state selected
by the menu governor may be greater than the actual time to the next
tick and that means lost energy.
To avoid that, make tick_nohz_get_sleep_length() return the current
time to the next event (before stopping the tick) in addition to the
estimated one via an extra pointer argument and make menu_select()
use that value to refine the state selection when necessary.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Diffstat (limited to 'kernel/time/tick-sched.c')
| -rw-r--r-- | kernel/time/tick-sched.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index c57c98c7e953..edb9d49b4996 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -1023,10 +1023,11 @@ bool tick_nohz_idle_got_tick(void) /** * tick_nohz_get_sleep_length - return the expected length of the current sleep + * @delta_next: duration until the next event if the tick cannot be stopped * * Called from power state control code with interrupts disabled */ -ktime_t tick_nohz_get_sleep_length(void) +ktime_t tick_nohz_get_sleep_length(ktime_t *delta_next) { struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev); struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); @@ -1040,12 +1041,14 @@ ktime_t tick_nohz_get_sleep_length(void) WARN_ON_ONCE(!ts->inidle); + *delta_next = ktime_sub(dev->next_event, now); + if (!can_stop_idle_tick(cpu, ts)) - goto out_dev; + return *delta_next; next_event = tick_nohz_next_event(ts, cpu); if (!next_event) - goto out_dev; + return *delta_next; /* * If the next highres timer to expire is earlier than next_event, the @@ -1055,9 +1058,6 @@ ktime_t tick_nohz_get_sleep_length(void) hrtimer_next_event_without(&ts->sched_timer)); return ktime_sub(next_event, now); - -out_dev: - return ktime_sub(dev->next_event, now); } /** |