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-rw-r--r--kernel/sched/rt.c83
1 files changed, 68 insertions, 15 deletions
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 @@ skip:
*/
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)))