This is a note to let you know that I've just added the patch titled
tick/sched: Optimize tick_do_update_jiffies64() further
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tick-sched-optimize-tick_do_update_jiffies64-further.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 0259d65a05de18da3dc82eab1030aab889f12714
Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Date: Tue Nov 17 14:19:47 2020 +0100
tick/sched: Optimize tick_do_update_jiffies64() further
[ Upstream commit 7a35bf2a6a871cd0252cd371d741e7d070b53af9 ]
Now that it's clear that there is always one tick to account, simplify the
calculations some more.
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20201117132006.565663056@xxxxxxxxxxxxx
Stable-dep-of: e9523a0d8189 ("tick/common: Align tick period with the HZ tick.")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index eaeeb4bb1f8ab..3b00167656d78 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -53,7 +53,7 @@ static ktime_t last_jiffies_update;
*/
static void tick_do_update_jiffies64(ktime_t now)
{
- unsigned long ticks = 0;
+ unsigned long ticks = 1;
ktime_t delta;
/*
@@ -91,20 +91,21 @@ static void tick_do_update_jiffies64(ktime_t now)
write_seqcount_begin(&jiffies_seq);
- last_jiffies_update = ktime_add(last_jiffies_update, tick_period);
-
delta = ktime_sub(now, tick_next_period);
if (unlikely(delta >= tick_period)) {
/* Slow path for long idle sleep times */
s64 incr = ktime_to_ns(tick_period);
- ticks = ktime_divns(delta, incr);
+ ticks += ktime_divns(delta, incr);
last_jiffies_update = ktime_add_ns(last_jiffies_update,
incr * ticks);
+ } else {
+ last_jiffies_update = ktime_add(last_jiffies_update,
+ tick_period);
}
- do_timer(++ticks);
+ do_timer(ticks);
/*
* Keep the tick_next_period variable up to date. WRITE_ONCE()
