Messages in this thread | | | Date | Mon, 5 Jun 2023 23:29:37 +0200 | From | Frederic Weisbecker <> | Subject | Re: [PATCH v7 02/21] timer: Do not IPI for deferrable timers |
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Le Wed, May 24, 2023 at 09:06:10AM +0200, Anna-Maria Behnsen a écrit : > 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 and 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> > --- > v6: new patch > --- > kernel/time/timer.c | 15 ++++++--------- > 1 file changed, 6 insertions(+), 9 deletions(-) > > diff --git a/kernel/time/timer.c b/kernel/time/timer.c > index 63a8ce7177dd..6e251e3cf659 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 CPU from going idle and are not > + * taken into account on idle path. An IPI when a new deferrable
Just to make sure everyone is aware that this concerns also nohz_full, this could be:
/* * Deferrable timers do not prevent CPU from entering dynticks * and are not taken into account on 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 remote IPI for deferrable timers completely. */
But anyway:
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
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