From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
Frederic Weisbecker <frederic@kernel.org>,
Yunfeng Ye <yeyunfeng@huawei.com>
Subject: [patch 5/7] tick/sched: Optimize tick_do_update_jiffies64() further
Date: Tue, 17 Nov 2020 14:19:47 +0100 [thread overview]
Message-ID: <20201117132006.565663056@linutronix.de> (raw)
In-Reply-To: 20201117131942.515430545@linutronix.de
Now that it's clear that there is always one tick to account, simplify the
calculations some more.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
kernel/time/tick-sched.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -55,7 +55,7 @@ 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;
/*
@@ -93,20 +93,21 @@ static void tick_do_update_jiffies64(kti
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()
next prev parent reply other threads:[~2020-11-17 14:24 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-17 13:19 [patch 0/7] tick: Cleanups and reduce jiffies_seq held times Thomas Gleixner
2020-11-17 13:19 ` [patch 1/7] tick/broadcast: Serialize access to tick_next_period Thomas Gleixner
2020-11-19 9:55 ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2020-11-17 13:19 ` [patch 2/7] tick: Document protections for tick related data Thomas Gleixner
2020-11-19 9:55 ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2020-11-17 13:19 ` [patch 3/7] tick/sched: Use tick_next_period for lockless quick check Thomas Gleixner
2020-11-19 9:55 ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2020-11-17 13:19 ` [patch 4/7] tick/sched: Reduce seqcount held scope in tick_do_update_jiffies64() Thomas Gleixner
2020-11-19 9:55 ` [tip: timers/core] " tip-bot2 for Yunfeng Ye
2020-11-17 13:19 ` Thomas Gleixner [this message]
2020-11-19 9:55 ` [tip: timers/core] tick/sched: Optimize tick_do_update_jiffies64() further tip-bot2 for Thomas Gleixner
2020-11-17 13:19 ` [patch 6/7] tick/sched: Release seqcount before invoking calc_load_global() Thomas Gleixner
2020-11-19 9:55 ` [tip: timers/core] " tip-bot2 for Yunfeng Ye
2020-11-17 13:19 ` [patch 7/7] tick: Get rid of tick_period Thomas Gleixner
2020-11-19 9:55 ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
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