From 338b1c7a49fe879af6df08db647bd6ea8729c72f Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Wed, 29 Dec 2021 12:12:56 +0800 Subject: [PATCH] tick/sched: Optimize tick_do_update_jiffies64() further mainline inclusion from mainline-5.11-rc1 commit 7a35bf2a6a871cd0252cd371d741e7d070b53af9 category: feature feature: Deep isolation bugzilla: https://gitee.com/openeuler/kernel/issues/I4N00D CVE: NA Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7a35bf2a6a871cd0252cd371d741e7d070b53af9 -------------------------------- Now that it's clear that there is always one tick to account, simplify the calculations some more. Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20201117132006.565663056@linutronix.de Signed-off-by: Yunfeng Ye Reviewed-by: Chao Liu Reviewed-by: Chen Hui Acked-by: Xie XiuQi Signed-off-by: Zheng Zengkai --- kernel/time/tick-sched.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index a2a26a8feae6..2b1eb5038a1f 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() -- GitLab