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Commit 3df29117 authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Greg Kroah-Hartman
Browse files

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: default avatarThomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20201117132006.565663056@linutronix.de


Stable-dep-of: e9523a0d8189 ("tick/common: Align tick period with the HZ tick.")
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent b6fe34d9

kernel/time/tick-sched.c

+6 −5
Original line number Diff line number Diff line
@@ -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()