diff options
| author | Anna-Maria Behnsen <anna-maria@linutronix.de> | 2023-12-01 10:26:28 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2023-12-20 16:49:38 +0100 |
| commit | d124c3393e798b1fb142ee728d5c8976d11e722d (patch) | |
| tree | 458ebf8804f3a74fd641a4dbe5ad8c39af5bab60 | |
| parent | b573c73101d8786446535b2ab28cbc8907bda9a9 (diff) | |
timers: Do not IPI for deferrable timers
Deferrable timers do not prevent CPU from going idle and are not taken into
account on idle path. Sending an IPI to a remote CPU when a new first
deferrable timer was enqueued will wake up the remote CPU but nothing will
be done regarding the deferrable timers.
Drop IPI completely when a new first deferrable timer was enqueued.
Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20231201092654.34614-7-anna-maria@linutronix.de
| -rw-r--r-- | kernel/time/timer.c | 15 |
1 files changed, 6 insertions, 9 deletions
diff --git a/kernel/time/timer.c b/kernel/time/timer.c index ed8d6063d9ef..91882059bf3d 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -571,18 +571,15 @@ static int calc_wheel_index(unsigned long expires, unsigned long clk, static void trigger_dyntick_cpu(struct timer_base *base, struct timer_list *timer) { - if (!is_timers_nohz_active()) - return; - /* - * TODO: This wants some optimizing similar to the code below, but we - * will do that when we switch from push to pull for deferrable timers. + * Deferrable timers do not prevent the CPU from entering dynticks and + * are not taken into account on the idle/nohz_full path. An IPI when a + * new deferrable timer is enqueued will wake up the remote CPU but + * nothing will be done with the deferrable timer base. Therefore skip + * the remote IPI for deferrable timers completely. */ - if (timer->flags & TIMER_DEFERRABLE) { - if (tick_nohz_full_cpu(base->cpu)) - wake_up_nohz_cpu(base->cpu); + if (!is_timers_nohz_active() || timer->flags & TIMER_DEFERRABLE) return; - } /* * We might have to IPI the remote CPU if the base is idle and the |