Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit af5ab277 authored by Arjan van de Ven's avatar Arjan van de Ven Committed by Thomas Gleixner
Browse files

clockevents: Remove the per cpu tick skew 



Historically, Linux has tried to make the regular timer tick on the
various CPUs not happen at the same time, to avoid contention on
xtime_lock.

Nowadays, with the tickless kernel, this contention no longer happens
since time keeping and updating are done differently. In addition,
this skew is actually hurting power consumption in a measurable way on
many-core systems.

Signed-off-by: default avatarArjan van de Ven <arjan@linux.intel.com>
LKML-Reference: <20100727210210.58d3118c@infradead.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 2b08de00

kernel/time/tick-sched.c

+0 −5
Original line number Original line Diff line number Diff line
@@ -780,7 +780,6 @@ void tick_setup_sched_timer(void) 
{

{

	struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched);

	struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched);

	ktime_t now = ktime_get();

	ktime_t now = ktime_get();

	u64 offset;





	/*

	/*

	 * Emulate tick processing via per-CPU hrtimers:

	 * Emulate tick processing via per-CPU hrtimers:
@@ -790,10 +789,6 @@ void tick_setup_sched_timer(void) 




	/* Get the next period (per cpu) */

	/* Get the next period (per cpu) */

	hrtimer_set_expires(&ts->sched_timer, tick_init_jiffy_update());

	hrtimer_set_expires(&ts->sched_timer, tick_init_jiffy_update());

	offset = ktime_to_ns(tick_period) >> 1;

	do_div(offset, num_possible_cpus());

	offset *= smp_processor_id();

	hrtimer_add_expires_ns(&ts->sched_timer, offset);





	for (;;) {

	for (;;) {

		hrtimer_forward(&ts->sched_timer, now, tick_period);

		hrtimer_forward(&ts->sched_timer, now, tick_period);