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

Commit f6ff4f01 authored by Prasad Sodagudi's avatar Prasad Sodagudi Committed by Runmin Wang
Browse files

sched: Add a check for cpu unbound deferrable timers 



Add a check for cpu unbound deferrable timer expiry and raise
softirq for handling the expired timers so that the CPU can
process the cpu unbound deferrable times as early as possible
when a cpu tries to enter/exit idle loop.

Change-Id: Ieffa74fa22a4d25493f5590b5ac1e0d784fcbbad
Signed-off-by: default avatarPrasad Sodagudi <psodagud@codeaurora.org>
parent 2e6001c5

include/linux/timer.h

+3 −0
Original line number Diff line number Diff line
@@ -202,6 +202,9 @@ extern void add_timer_on(struct timer_list *timer, int cpu); 
extern int del_timer(struct timer_list * timer);

extern int mod_timer(struct timer_list *timer, unsigned long expires);

extern int mod_timer_pending(struct timer_list *timer, unsigned long expires);

#ifdef CONFIG_SMP

extern bool check_pending_deferrable_timers(int cpu);

#endif



/*

 * The jiffies value which is added to now, when there is no timer

kernel/time/tick-sched.c

+6 −0
Original line number Diff line number Diff line
@@ -26,6 +26,7 @@ 
#include <linux/module.h>

#include <linux/irq_work.h>

#include <linux/posix-timers.h>

#include <linux/timer.h>

#include <linux/context_tracking.h>

#include <linux/rq_stats.h>
@@ -946,6 +947,11 @@ static void __tick_nohz_idle_enter(struct tick_sched *ts) 


	now = tick_nohz_start_idle(ts);



#ifdef CONFIG_SMP

	if (check_pending_deferrable_timers(cpu))

		raise_softirq_irqoff(TIMER_SOFTIRQ);

#endif



	if (can_stop_idle_tick(cpu, ts)) {

		int was_stopped = ts->tick_stopped;

kernel/time/timer.c

+31 −1
Original line number Diff line number Diff line
@@ -210,6 +210,7 @@ struct timer_base { 


static DEFINE_PER_CPU(struct timer_base, timer_bases[NR_BASES]);

struct timer_base timer_base_deferrable;

static atomic_t deferrable_pending;



#if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON)

unsigned int sysctl_timer_migration = 1;
@@ -1488,6 +1489,31 @@ static u64 cmp_next_hrtimer_event(u64 basem, u64 expires) 
	return DIV_ROUND_UP_ULL(nextevt, TICK_NSEC) * TICK_NSEC;

}





#ifdef CONFIG_SMP

/*

 * check_pending_deferrable_timers - Check for unbound deferrable timer expiry

 * @cpu - Current CPU

 *

 * The function checks whether any global deferrable pending timers

 * are exipired or not. This function does not check cpu bounded

 * diferrable pending timers expiry.

 *

 * The function returns true when a cpu unbounded deferrable timer is expired.

 */

bool check_pending_deferrable_timers(int cpu)

{

	if (cpu == tick_do_timer_cpu ||

		tick_do_timer_cpu == TICK_DO_TIMER_NONE) {

		if (time_after_eq(jiffies, timer_base_deferrable.clk)

			&& !atomic_cmpxchg(&deferrable_pending, 0, 1)) {

			return true;

		}

	}

	return false;

}

#endif



/**

 * get_next_timer_interrupt - return the time (clock mono) of the next timer

 * @basej:	base time jiffies
@@ -1669,8 +1695,12 @@ static __latent_entropy void run_timer_softirq(struct softirq_action *h) 
	__run_timers(base);

	if (IS_ENABLED(CONFIG_NO_HZ_COMMON)) {

		__run_timers(this_cpu_ptr(&timer_bases[BASE_DEF]));

		__run_timers(&timer_base_deferrable);

	}



	if ((atomic_cmpxchg(&deferrable_pending, 1, 0) &&

		tick_do_timer_cpu == TICK_DO_TIMER_NONE) ||

		tick_do_timer_cpu == smp_processor_id())

		__run_timers(&timer_base_deferrable);

}



/*