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Commit b79f3833 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

sched: rt: fix SMP bandwidth balancing for throttled groups 



Now we exceed the runtime and get throttled - the period rollover tick
will subtract the cpu quota from the runtime and check if we're below
quota. However with this cpu having a very small portion of the runtime
it will not refresh as fast as it should.

Therefore, also rebalance the runtime when we're throttled.

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: "Daniel K." <dk@uw.no>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent ada18de2

kernel/sched_rt.c

+29 −12
Original line number Diff line number Diff line
@@ -228,6 +228,28 @@ static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq) 


#endif



#ifdef CONFIG_SMP

static int do_balance_runtime(struct rt_rq *rt_rq);



static int balance_runtime(struct rt_rq *rt_rq)

{

	int more = 0;



	if (rt_rq->rt_time > rt_rq->rt_runtime) {

		spin_unlock(&rt_rq->rt_runtime_lock);

		more = do_balance_runtime(rt_rq);

		spin_lock(&rt_rq->rt_runtime_lock);

	}



	return more;

}

#else

static inline int balance_runtime(struct rt_rq *rt_rq)

{

	return 0;

}

#endif



static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)

{

	int i, idle = 1;
@@ -247,6 +269,8 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun) 
			u64 runtime;



			spin_lock(&rt_rq->rt_runtime_lock);

			if (rt_rq->rt_throttled)

				balance_runtime(rt_rq);

			runtime = rt_rq->rt_runtime;

			rt_rq->rt_time -= min(rt_rq->rt_time, overrun*runtime);

			if (rt_rq->rt_throttled && rt_rq->rt_time < runtime) {
@@ -267,7 +291,7 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun) 
}



#ifdef CONFIG_SMP

static int balance_runtime(struct rt_rq *rt_rq)

static int do_balance_runtime(struct rt_rq *rt_rq)

{

	struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);

	struct root_domain *rd = cpu_rq(smp_processor_id())->rd;
@@ -428,17 +452,10 @@ static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq) 
	if (sched_rt_runtime(rt_rq) >= sched_rt_period(rt_rq))

		return 0;



#ifdef CONFIG_SMP

	if (rt_rq->rt_time > runtime) {

		spin_unlock(&rt_rq->rt_runtime_lock);

	balance_runtime(rt_rq);

		spin_lock(&rt_rq->rt_runtime_lock);



	runtime = sched_rt_runtime(rt_rq);

	if (runtime == RUNTIME_INF)

		return 0;

	}

#endif



	if (rt_rq->rt_time > runtime) {

		rt_rq->rt_throttled = 1;