[RFC PATCH 06/10] timer: Reuse next expiry cache after nohz exit

Frederic Weisbecker
2020-07-01T01:11:08Z

Now that we track the next expiry unconditionally when a timer is added,
we can reuse that information on a tick firing after exiting nohz.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Juri Lelli <juri.lelli@redhat.com>
---
kernel/time/timer.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 30f491ec875a..4612d26fd09a 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -1697,13 +1697,11 @@ static int collect_expired_timers(struct timer_base *base,
* the next expiring timer.
*/
if ((long)(now - base->clk) > 2) {
- unsigned long next = __next_timer_interrupt(base);
-
/*
* If the next timer is ahead of time forward to current
* jiffies, otherwise forward to the next expiry time:
*/
- if (time_after(next, now)) {
+ if (time_after(base->next_expiry, now)) {
/*
* The call site will increment base->clk and then
* terminate the expiry loop immediately.
@@ -1711,7 +1709,7 @@ static int collect_expired_timers(struct timer_base *base,
base->clk = now;
return 0;
}
- base->clk = next;
+ base->clk = base->next_expiry;
}
return __collect_expired_timers(base, heads);
}
--
2.26.2