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

Commit dce75a8c authored by John Stultz's avatar John Stultz
Browse files

alarmtimers: Add alarm_forward functionality 



In order to avoid wasting time expiring and re-adding very high freq
periodic alarmtimers, introduce alarm_forward() which is similar to
hrtimer_forward and moves the timer to the next future expiration time
and returns the number of overruns.

CC: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarJohn Stultz <john.stultz@linaro.org>
parent 54da23b7

include/linux/alarmtimer.h

+2 −0
Original line number Original line Diff line number Diff line
@@ -42,4 +42,6 @@ void alarm_init(struct alarm *alarm, enum alarmtimer_type type, 
void alarm_start(struct alarm *alarm, ktime_t start, ktime_t period);

void alarm_start(struct alarm *alarm, ktime_t start, ktime_t period);

void alarm_cancel(struct alarm *alarm);

void alarm_cancel(struct alarm *alarm);





u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval);



#endif
 
#endif

kernel/time/alarmtimer.c

+36 −1
Original line number Original line Diff line number Diff line
@@ -347,6 +347,41 @@ void alarm_cancel(struct alarm *alarm) 
}

}











u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval)

{

	u64 overrun = 1;

	ktime_t delta;



	delta = ktime_sub(now, alarm->node.expires);



	if (delta.tv64 < 0)

		return 0;



	if (unlikely(delta.tv64 >= interval.tv64)) {

		s64 incr = ktime_to_ns(interval);



		overrun = ktime_divns(delta, incr);



		alarm->node.expires = ktime_add_ns(alarm->node.expires,

							incr*overrun);



		if (alarm->node.expires.tv64 > now.tv64)

			return overrun;

		/*

		 * This (and the ktime_add() below) is the

		 * correction for exact:

		 */

		overrun++;

	}



	alarm->node.expires = ktime_add(alarm->node.expires, interval);

	return overrun;

}









/**

/**

 * clock2alarm - helper that converts from clockid to alarmtypes

 * clock2alarm - helper that converts from clockid to alarmtypes

 * @clockid: clockid.

 * @clockid: clockid.
@@ -376,7 +411,7 @@ static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm, 




	/* Re-add periodic timers */

	/* Re-add periodic timers */

	if (alarm->period.tv64) {

	if (alarm->period.tv64) {

		alarm->node.expires = ktime_add(now, alarm->period);

		ptr->it_overrun += alarm_forward(alarm, now, alarm->period);

		return ALARMTIMER_RESTART;

		return ALARMTIMER_RESTART;

	}

	}

	return ALARMTIMER_NORESTART;

	return ALARMTIMER_NORESTART;