Messages in this thread Patch in this message | | | From | Anna-Maria Behnsen <> | Subject | [PATCH v4 10/16] timer: Add get next timer interrupt functionality for remote CPUs | Date | Fri, 4 Nov 2022 15:57:31 +0100 |
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To prepare for the conversion of the NOHZ timer placement to a pull at expiry time model it's required to have functionality available getting the next timer interrupt on a remote CPU.
Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de> --- kernel/time/tick-internal.h | 3 +++ kernel/time/timer.c | 41 +++++++++++++++++++++++++++++++++++++ 2 files changed, 44 insertions(+)
diff --git a/kernel/time/tick-internal.h b/kernel/time/tick-internal.h index 6f5f164506d5..7b65abc9d803 100644 --- a/kernel/time/tick-internal.h +++ b/kernel/time/tick-internal.h @@ -170,6 +170,9 @@ DECLARE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases); extern void forward_and_idle_timer_bases(unsigned long basej, u64 basem, struct timer_events *tevt); +extern void get_next_timer_interrupt_remote(unsigned long basej, u64 basem, + struct timer_events *tevt, + unsigned int cpu); void timer_clear_idle(void); #define CLOCK_SET_WALL \ diff --git a/kernel/time/timer.c b/kernel/time/timer.c index 853089febf83..1b82661f6172 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -1759,6 +1759,47 @@ static void forward_base_clk(struct timer_base *base, unsigned long nextevt, } } +/** + * get_next_timer_interrupt_remote + * @basej: base time jiffies + * @basem: base time clock monotonic + * @tevt: Pointer to the storage for the expiry values + * @cpu: Remote CPU + * + * Stores the next pending local and global timer expiry values in the + * struct pointed to by @tevt. If a queue is empty the corresponding + * field is set to KTIME_MAX. If local event expires before global + * event, global event is set to KTIME_MAX as well. + */ +void get_next_timer_interrupt_remote(unsigned long basej, u64 basem, + struct timer_events *tevt, + unsigned int cpu) +{ + struct timer_base *base_local, *base_global; + unsigned long flags; + + /* Preset local / global events */ + tevt->local = tevt->global = KTIME_MAX; + + /* + * Pretend that there is no timer pending if the cpu is offline. + * Possible pending timers will be migrated later to an active cpu. + */ + if (cpu_is_offline(cpu)) + return; + + base_local = per_cpu_ptr(&timer_bases[BASE_LOCAL], cpu); + base_global = per_cpu_ptr(&timer_bases[BASE_GLOBAL], cpu); + + raw_spin_lock_irqsave(&base_local->lock, flags); + raw_spin_lock_nested(&base_global->lock, SINGLE_DEPTH_NESTING); + + get_next_timer_interrupt(base_local, base_global, basej, basem, tevt); + + raw_spin_unlock(&base_global->lock); + raw_spin_unlock_irqrestore(&base_local->lock, flags); +} + /** * forward_and_idle_timer_bases * @basej: base time jiffies -- 2.30.2
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