X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=blobdiff_plain;f=kernel%2Fsched%2Frt.c;h=4043abe45459df664d96351030966fb7104384e2;hb=4104a562e0ca62e971089db9d3c47794a0d7d4eb;hp=e591d40fd645e451e79946fc9801ee24e72ef68e;hpb=1daa56bcfd8b329447e0c1b1e91c3925d08489b7;p=linux.git

diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index e591d40fd645..4043abe45459 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -437,6 +437,45 @@ static inline int on_rt_rq(struct sched_rt_entity *rt_se)
 	return rt_se->on_rq;
 }
 
+#ifdef CONFIG_UCLAMP_TASK
+/*
+ * Verify the fitness of task @p to run on @cpu taking into account the uclamp
+ * settings.
+ *
+ * This check is only important for heterogeneous systems where uclamp_min value
+ * is higher than the capacity of a @cpu. For non-heterogeneous system this
+ * function will always return true.
+ *
+ * The function will return true if the capacity of the @cpu is >= the
+ * uclamp_min and false otherwise.
+ *
+ * Note that uclamp_min will be clamped to uclamp_max if uclamp_min
+ * > uclamp_max.
+ */
+static inline bool rt_task_fits_capacity(struct task_struct *p, int cpu)
+{
+	unsigned int min_cap;
+	unsigned int max_cap;
+	unsigned int cpu_cap;
+
+	/* Only heterogeneous systems can benefit from this check */
+	if (!static_branch_unlikely(&sched_asym_cpucapacity))
+		return true;
+
+	min_cap = uclamp_eff_value(p, UCLAMP_MIN);
+	max_cap = uclamp_eff_value(p, UCLAMP_MAX);
+
+	cpu_cap = capacity_orig_of(cpu);
+
+	return cpu_cap >= min(min_cap, max_cap);
+}
+#else
+static inline bool rt_task_fits_capacity(struct task_struct *p, int cpu)
+{
+	return true;
+}
+#endif
+
 #ifdef CONFIG_RT_GROUP_SCHED
 
 static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
@@ -1391,6 +1430,7 @@ select_task_rq_rt(struct task_struct *p, int cpu, int sd_flag, int flags)
 {
 	struct task_struct *curr;
 	struct rq *rq;
+	bool test;
 
 	/* For anything but wake ups, just return the task_cpu */
 	if (sd_flag != SD_BALANCE_WAKE && sd_flag != SD_BALANCE_FORK)
@@ -1422,10 +1462,16 @@ select_task_rq_rt(struct task_struct *p, int cpu, int sd_flag, int flags)
 	 *
 	 * This test is optimistic, if we get it wrong the load-balancer
 	 * will have to sort it out.
+	 *
+	 * We take into account the capacity of the CPU to ensure it fits the
+	 * requirement of the task - which is only important on heterogeneous
+	 * systems like big.LITTLE.
 	 */
-	if (curr && unlikely(rt_task(curr)) &&
-	    (curr->nr_cpus_allowed < 2 ||
-	     curr->prio <= p->prio)) {
+	test = curr &&
+	       unlikely(rt_task(curr)) &&
+	       (curr->nr_cpus_allowed < 2 || curr->prio <= p->prio);
+
+	if (test || !rt_task_fits_capacity(p, cpu)) {
 		int target = find_lowest_rq(p);
 
 		/*
@@ -1449,15 +1495,15 @@ static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p)
 	 * let's hope p can move out.
 	 */
 	if (rq->curr->nr_cpus_allowed == 1 ||
-	    !cpupri_find(&rq->rd->cpupri, rq->curr, NULL))
+	    !cpupri_find(&rq->rd->cpupri, rq->curr, NULL, NULL))
 		return;
 
 	/*
 	 * p is migratable, so let's not schedule it and
 	 * see if it is pushed or pulled somewhere else.
 	 */
-	if (p->nr_cpus_allowed != 1
-	    && cpupri_find(&rq->rd->cpupri, p, NULL))
+	if (p->nr_cpus_allowed != 1 &&
+	    cpupri_find(&rq->rd->cpupri, p, NULL, NULL))
 		return;
 
 	/*
@@ -1601,7 +1647,8 @@ static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
 static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu)
 {
 	if (!task_running(rq, p) &&
-	    cpumask_test_cpu(cpu, p->cpus_ptr))
+	    cpumask_test_cpu(cpu, p->cpus_ptr) &&
+	    rt_task_fits_capacity(p, cpu))
 		return 1;
 
 	return 0;
@@ -1643,7 +1690,8 @@ static int find_lowest_rq(struct task_struct *task)
 	if (task->nr_cpus_allowed == 1)
 		return -1; /* No other targets possible */
 
-	if (!cpupri_find(&task_rq(task)->rd->cpupri, task, lowest_mask))
+	if (!cpupri_find(&task_rq(task)->rd->cpupri, task, lowest_mask,
+			 rt_task_fits_capacity))
 		return -1; /* No targets found */
 
 	/*
@@ -2147,12 +2195,14 @@ static void pull_rt_task(struct rq *this_rq)
  */
 static void task_woken_rt(struct rq *rq, struct task_struct *p)
 {
-	if (!task_running(rq, p) &&
-	    !test_tsk_need_resched(rq->curr) &&
-	    p->nr_cpus_allowed > 1 &&
-	    (dl_task(rq->curr) || rt_task(rq->curr)) &&
-	    (rq->curr->nr_cpus_allowed < 2 ||
-	     rq->curr->prio <= p->prio))
+	bool need_to_push = !task_running(rq, p) &&
+			    !test_tsk_need_resched(rq->curr) &&
+			    p->nr_cpus_allowed > 1 &&
+			    (dl_task(rq->curr) || rt_task(rq->curr)) &&
+			    (rq->curr->nr_cpus_allowed < 2 ||
+			     rq->curr->prio <= p->prio);
+
+	if (need_to_push || !rt_task_fits_capacity(p, cpu_of(rq)))
 		push_rt_tasks(rq);
 }
 
@@ -2224,7 +2274,10 @@ static void switched_to_rt(struct rq *rq, struct task_struct *p)
 	 */
 	if (task_on_rq_queued(p) && rq->curr != p) {
 #ifdef CONFIG_SMP
-		if (p->nr_cpus_allowed > 1 && rq->rt.overloaded)
+		bool need_to_push = rq->rt.overloaded ||
+				    !rt_task_fits_capacity(p, cpu_of(rq));
+
+		if (p->nr_cpus_allowed > 1 && need_to_push)
 			rt_queue_push_tasks(rq);
 #endif /* CONFIG_SMP */
 		if (p->prio < rq->curr->prio && cpu_online(cpu_of(rq)))