| From | Anna-Maria Behnsen <> | Subject | [PATCH v9 16/32] timers: Optimization for timer_base_try_to_set_idle() | Date | Fri, 1 Dec 2023 10:26:38 +0100 |
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When tick is stopped also the timer base is_idle flag is set. When reentering the timer_base_try_to_set_idle() with the tick stopped, there is no need to check whether the timer base needs to be set idle again. When a timer was enqueued in the meantime, this is already handled by the nohz_get_next_event() call which was executed before tick_nohz_stop_tick().
Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de> --- v9: New, as this optimization was splitted from the patch before. --- kernel/time/tick-sched.c | 2 +- kernel/time/timer.c | 11 ++++++++--- 2 files changed, 9 insertions(+), 4 deletions(-)
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 3e1cdb7c6966..c6b415052c56 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -886,7 +886,7 @@ static void tick_nohz_stop_tick(struct tick_sched *ts, int cpu) struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev); unsigned long basejiff = ts->last_jiffies; u64 basemono = ts->timer_expires_base; - bool timer_idle; + bool timer_idle = ts->tick_stopped; u64 expires; /* Make sure we won't be trying to stop it twice in a row. */ diff --git a/kernel/time/timer.c b/kernel/time/timer.c index df6558f62e6f..177bcde8a2c0 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -1996,13 +1996,18 @@ u64 get_next_timer_interrupt(unsigned long basej, u64 basem) * timer_base_try_to_set_idle() - Try to set the idle state of the timer bases * @basej: base time jiffies * @basem: base time clock monotonic - * @idle: pointer to store the value of timer_base->is_idle + * @idle: pointer to store the value of timer_base->is_idle on return; + * *idle contains the information whether tick was already stopped * - * Returns the tick aligned clock monotonic time of the next pending - * timer or KTIME_MAX if no timer is pending. + * Returns the tick aligned clock monotonic time of the next pending timer or + * KTIME_MAX if no timer is pending. When tick was already stopped KTIME_MAX is + * returned as well. */ u64 timer_base_try_to_set_idle(unsigned long basej, u64 basem, bool *idle) { + if (*idle) + return KTIME_MAX; + return __get_next_timer_interrupt(basej, basem, idle); } -- 2.39.2
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