diff mbox series

[v8,06/25] timers: Split out forward timer base functionality

Message ID 20231004123454.15691-7-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 Oct. 4, 2023, 12:34 p.m. UTC 
  Forwarding timer base is done when the next expiry value is calculated and
when a new timer is enqueued. When the next expiry value is calculated the
jiffies value is already available and does not need to be reread a second
time.

Splitting out the forward timer base functionality to make it executable
via both contextes - those where jiffies are already known and those, where
jiffies need to be read.

No functional change.

Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
---
 kernel/time/timer.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

Comments

Frederic Weisbecker Oct. 6, 2023, 11:16 a.m. UTC | #1 
On Wed, Oct 04, 2023 at 02:34:35PM +0200, Anna-Maria Behnsen wrote:
> Forwarding timer base is done when the next expiry value is calculated and
> when a new timer is enqueued. When the next expiry value is calculated the
> jiffies value is already available and does not need to be reread a second
> time.
> 
> Splitting out the forward timer base functionality to make it executable
> via both contextes - those where jiffies are already known and those, where
> jiffies need to be read.
> 
> No functional change.
> 
> Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>

Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
diff mbox series

Patch

diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 31aed8353db1..2f6afd1da891 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -939,30 +939,34 @@  get_target_base(struct timer_base *base, unsigned tflags)
 	return get_timer_this_cpu_base(tflags);
 }
 
-static inline void forward_timer_base(struct timer_base *base)
+static inline void __forward_timer_base(struct timer_base *base,
+					unsigned long basej)
 {
-	unsigned long jnow = READ_ONCE(jiffies);
-
 	/*
 	 * Check whether we can forward the base. We can only do that when
 	 * @basej is past base->clk otherwise we might rewind base->clk.
 	 */
-	if (time_before_eq(jnow, base->clk))
+	if (time_before_eq(basej, base->clk))
 		return;
 
 	/*
 	 * If the next expiry value is > jiffies, then we fast forward to
 	 * jiffies otherwise we forward to the next expiry value.
 	 */
-	if (time_after(base->next_expiry, jnow)) {
-		base->clk = jnow;
+	if (time_after(base->next_expiry, basej)) {
+		base->clk = basej;
 	} else {
 		if (WARN_ON_ONCE(time_before(base->next_expiry, base->clk)))
 			return;
 		base->clk = base->next_expiry;
 	}
+
 }
 
+static inline void forward_timer_base(struct timer_base *base)
+{
+	__forward_timer_base(base, READ_ONCE(jiffies));
+}
 
 /*
  * We are using hashed locking: Holding per_cpu(timer_bases[x]).lock means