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Commit 61eadef6 authored by Mike Galbraith's avatar Mike Galbraith Committed by Ingo Molnar
Browse files

sched, rt: Update rq clock when unthrottling of an otherwise idle CPU 



If an RT task is awakened while it's rt_rq is throttled, the time between
wakeup/enqueue and unthrottle/selection may be accounted as rt_time
if the CPU is idle.  Set rq->skip_clock_update negative upon throttle
release to tell put_prev_task() that we need a clock update.

Reported-by: default avatarThomas Giesel <skoe@directbox.com>
Signed-off-by: default avatarMike Galbraith <efault@gmx.de>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1304059010.7472.1.camel@marge.simson.net


Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 3e51e3ed

kernel/sched.c

+3 −3
Original line number Original line Diff line number Diff line
@@ -466,7 +466,7 @@ struct rq { 
	u64 nohz_stamp;

	u64 nohz_stamp;

	unsigned char nohz_balance_kick;

	unsigned char nohz_balance_kick;

#endif

#endif

	unsigned int skip_clock_update;

	int skip_clock_update;





	/* capture load from *all* tasks on this cpu: */

	/* capture load from *all* tasks on this cpu: */

	struct load_weight load;

	struct load_weight load;
@@ -652,7 +652,7 @@ static void update_rq_clock(struct rq *rq) 
{

{

	s64 delta;

	s64 delta;





	if (rq->skip_clock_update)

	if (rq->skip_clock_update > 0)

		return;

		return;





	delta = sched_clock_cpu(cpu_of(rq)) - rq->clock;

	delta = sched_clock_cpu(cpu_of(rq)) - rq->clock;
@@ -4127,7 +4127,7 @@ static inline void schedule_debug(struct task_struct *prev) 




static void put_prev_task(struct rq *rq, struct task_struct *prev)

static void put_prev_task(struct rq *rq, struct task_struct *prev)

{

{

	if (prev->on_rq)

	if (prev->on_rq || rq->skip_clock_update < 0)

		update_rq_clock(rq);

		update_rq_clock(rq);

	prev->sched_class->put_prev_task(rq, prev);

	prev->sched_class->put_prev_task(rq, prev);

}

}

kernel/sched_rt.c

+7 −0
Original line number Original line Diff line number Diff line
@@ -562,6 +562,13 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun) 
			if (rt_rq->rt_throttled && rt_rq->rt_time < runtime) {

			if (rt_rq->rt_throttled && rt_rq->rt_time < runtime) {

				rt_rq->rt_throttled = 0;

				rt_rq->rt_throttled = 0;

				enqueue = 1;

				enqueue = 1;



				/*

				 * Force a clock update if the CPU was idle,

				 * lest wakeup -> unthrottle time accumulate.

				 */

				if (rt_rq->rt_nr_running && rq->curr == rq->idle)

					rq->skip_clock_update = -1;

			}

			}

			if (rt_rq->rt_time || rt_rq->rt_nr_running)

			if (rt_rq->rt_time || rt_rq->rt_nr_running)

				idle = 0;

				idle = 0;