diff mbox series

[v6,07/21] timers: Introduce add_timer() variants which modify timer flags

Message ID 20230510072817.116056-8-anna-maria@linutronix.de
State New
Headers
Series timer: Move from a push remote at enqueue to a pull at expiry model |

Commit Message

Anna-Maria Behnsen May 10, 2023, 7:28 a.m. UTC 
  Timer might be used as pinned timer (using add_timer_on()) and later on as
non pinned timers using add_timer(). When the NOHZ timer pull at expiry
model is in place, TIMER_PINNED flag is required to be used whenever a
timer needs to expire on a dedicated CPU. Flag must no be set, if
expiration on a dedicated CPU is not required.

add_timer_on()'s behavior will be changed during the preparation patches
for the NOHZ timer pull at expiry model to unconditionally set TIMER_PINNED
flag. To be able to reset/set the flag when queueing a timer, two variants
of add_timer() are introduced.

This is a preparatory patch and has no functional change.

Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
---
New in v6
---
 include/linux/timer.h |  2 ++
 kernel/time/timer.c   | 34 ++++++++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+)

Comments

Frederic Weisbecker June 5, 2023, 9:43 p.m. UTC | #1 
Le Wed, May 10, 2023 at 09:28:03AM +0200, Anna-Maria Behnsen a écrit :
> Timer might be used as pinned timer (using add_timer_on()) and later on as
> non pinned timers using add_timer(). When the NOHZ timer pull at expiry
> model is in place, TIMER_PINNED flag is required to be used whenever a
> timer needs to expire on a dedicated CPU. Flag must no be set, if
> expiration on a dedicated CPU is not required.
> 
> add_timer_on()'s behavior will be changed during the preparation patches
> for the NOHZ timer pull at expiry model to unconditionally set TIMER_PINNED
> flag. To be able to reset/set the flag when queueing a timer, two variants
> of add_timer() are introduced.
> 
> This is a preparatory patch and has no functional change.
> 
> Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
> ---
> New in v6
> ---
>  include/linux/timer.h |  2 ++
>  kernel/time/timer.c   | 34 ++++++++++++++++++++++++++++++++++
>  2 files changed, 36 insertions(+)
> 
> diff --git a/include/linux/timer.h b/include/linux/timer.h
> index 9162f275819a..6f96661480dd 100644
> --- a/include/linux/timer.h
> +++ b/include/linux/timer.h
> @@ -180,6 +180,8 @@ extern int timer_reduce(struct timer_list *timer, unsigned long expires);
>  #define NEXT_TIMER_MAX_DELTA	((1UL << 30) - 1)
>  
>  extern void add_timer(struct timer_list *timer);
> +extern void add_timer_local(struct timer_list *timer);
> +extern void add_timer_global(struct timer_list *timer);
>  
>  extern int try_to_del_timer_sync(struct timer_list *timer);
>  extern int timer_delete_sync(struct timer_list *timer);
> diff --git a/kernel/time/timer.c b/kernel/time/timer.c
> index 1522fb81887e..ab9a8bb11a8a 100644
> --- a/kernel/time/timer.c
> +++ b/kernel/time/timer.c
> @@ -1242,6 +1242,40 @@ void add_timer(struct timer_list *timer)
>  }
>  EXPORT_SYMBOL(add_timer);
>  
> +/**
> + * add_timer_local - Start a timer on the local CPU
> + * @timer:	The timer to be started
> + *
> + * Same as add_timer() except that the timer flag TIMER_PINNED is set.
> + *
> + * See add_timer() for further details.
> + */
> +void add_timer_local(struct timer_list *timer)
> +{
> +	if (WARN_ON_ONCE(timer_pending(timer)))
> +		return;
> +	timer->flags |= TIMER_PINNED;
> +	__mod_timer(timer, timer->expires, MOD_TIMER_NOTPENDING);
> +}
> +EXPORT_SYMBOL(add_timer_local);

This one doesn't seem to be used at the end of the patchset.

Thanks.
diff mbox series

Patch

diff --git a/include/linux/timer.h b/include/linux/timer.h
index 9162f275819a..6f96661480dd 100644
--- a/include/linux/timer.h
+++ b/include/linux/timer.h
@@ -180,6 +180,8 @@  extern int timer_reduce(struct timer_list *timer, unsigned long expires);
 #define NEXT_TIMER_MAX_DELTA	((1UL << 30) - 1)
 
 extern void add_timer(struct timer_list *timer);
+extern void add_timer_local(struct timer_list *timer);
+extern void add_timer_global(struct timer_list *timer);
 
 extern int try_to_del_timer_sync(struct timer_list *timer);
 extern int timer_delete_sync(struct timer_list *timer);
diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 1522fb81887e..ab9a8bb11a8a 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -1242,6 +1242,40 @@  void add_timer(struct timer_list *timer)
 }
 EXPORT_SYMBOL(add_timer);
 
+/**
+ * add_timer_local - Start a timer on the local CPU
+ * @timer:	The timer to be started
+ *
+ * Same as add_timer() except that the timer flag TIMER_PINNED is set.
+ *
+ * See add_timer() for further details.
+ */
+void add_timer_local(struct timer_list *timer)
+{
+	if (WARN_ON_ONCE(timer_pending(timer)))
+		return;
+	timer->flags |= TIMER_PINNED;
+	__mod_timer(timer, timer->expires, MOD_TIMER_NOTPENDING);
+}
+EXPORT_SYMBOL(add_timer_local);
+
+/**
+ * add_timer_global - Start a timer without TIMER_PINNED flag set
+ * @timer:	The timer to be started
+ *
+ * Same as add_timer() except that the timer flag TIMER_PINNED is unset.
+ *
+ * See add_timer() for further details.
+ */
+void add_timer_global(struct timer_list *timer)
+{
+	if (WARN_ON_ONCE(timer_pending(timer)))
+		return;
+	timer->flags &= ~TIMER_PINNED;
+	__mod_timer(timer, timer->expires, MOD_TIMER_NOTPENDING);
+}
+EXPORT_SYMBOL(add_timer_global);
+
 /**
  * add_timer_on - Start a timer on a particular CPU
  * @timer:	The timer to be started