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

[Frederic Weisbecker]

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 <frede...@kernel.org>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Anna-Maria Gleixner <anna-ma...@linutronix.de>
Cc: Juri Lelli <juri.le...@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