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-rw-r--r--kernel/sched.c160
1 files changed, 131 insertions, 29 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index 3ce26954be12..b6506671b2be 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -206,6 +206,7 @@ struct runqueue {
*/
unsigned long nr_running;
#ifdef CONFIG_SMP
+ unsigned long prio_bias;
unsigned long cpu_load[3];
#endif
unsigned long long nr_switches;
@@ -659,13 +660,68 @@ static int effective_prio(task_t *p)
return prio;
}
+#ifdef CONFIG_SMP
+static inline void inc_prio_bias(runqueue_t *rq, int prio)
+{
+ rq->prio_bias += MAX_PRIO - prio;
+}
+
+static inline void dec_prio_bias(runqueue_t *rq, int prio)
+{
+ rq->prio_bias -= MAX_PRIO - prio;
+}
+
+static inline void inc_nr_running(task_t *p, runqueue_t *rq)
+{
+ rq->nr_running++;
+ if (rt_task(p)) {
+ if (p != rq->migration_thread)
+ /*
+ * The migration thread does the actual balancing. Do
+ * not bias by its priority as the ultra high priority
+ * will skew balancing adversely.
+ */
+ inc_prio_bias(rq, p->prio);
+ } else
+ inc_prio_bias(rq, p->static_prio);
+}
+
+static inline void dec_nr_running(task_t *p, runqueue_t *rq)
+{
+ rq->nr_running--;
+ if (rt_task(p)) {
+ if (p != rq->migration_thread)
+ dec_prio_bias(rq, p->prio);
+ } else
+ dec_prio_bias(rq, p->static_prio);
+}
+#else
+static inline void inc_prio_bias(runqueue_t *rq, int prio)
+{
+}
+
+static inline void dec_prio_bias(runqueue_t *rq, int prio)
+{
+}
+
+static inline void inc_nr_running(task_t *p, runqueue_t *rq)
+{
+ rq->nr_running++;
+}
+
+static inline void dec_nr_running(task_t *p, runqueue_t *rq)
+{
+ rq->nr_running--;
+}
+#endif
+
/*
* __activate_task - move a task to the runqueue.
*/
static inline void __activate_task(task_t *p, runqueue_t *rq)
{
enqueue_task(p, rq->active);
- rq->nr_running++;
+ inc_nr_running(p, rq);
}
/*
@@ -674,7 +730,7 @@ static inline void __activate_task(task_t *p, runqueue_t *rq)
static inline void __activate_idle_task(task_t *p, runqueue_t *rq)
{
enqueue_task_head(p, rq->active);
- rq->nr_running++;
+ inc_nr_running(p, rq);
}
static int recalc_task_prio(task_t *p, unsigned long long now)
@@ -759,7 +815,8 @@ static void activate_task(task_t *p, runqueue_t *rq, int local)
}
#endif
- p->prio = recalc_task_prio(p, now);
+ if (!rt_task(p))
+ p->prio = recalc_task_prio(p, now);
/*
* This checks to make sure it's not an uninterruptible task
@@ -793,7 +850,7 @@ static void activate_task(task_t *p, runqueue_t *rq, int local)
*/
static void deactivate_task(struct task_struct *p, runqueue_t *rq)
{
- rq->nr_running--;
+ dec_nr_running(p, rq);
dequeue_task(p, p->array);
p->array = NULL;
}
@@ -808,21 +865,28 @@ static void deactivate_task(struct task_struct *p, runqueue_t *rq)
#ifdef CONFIG_SMP
static void resched_task(task_t *p)
{
- int need_resched, nrpolling;
+ int cpu;
assert_spin_locked(&task_rq(p)->lock);
- /* minimise the chance of sending an interrupt to poll_idle() */
- nrpolling = test_tsk_thread_flag(p,TIF_POLLING_NRFLAG);
- need_resched = test_and_set_tsk_thread_flag(p,TIF_NEED_RESCHED);
- nrpolling |= test_tsk_thread_flag(p,TIF_POLLING_NRFLAG);
+ if (unlikely(test_tsk_thread_flag(p, TIF_NEED_RESCHED)))
+ return;
+
+ set_tsk_thread_flag(p, TIF_NEED_RESCHED);
+
+ cpu = task_cpu(p);
+ if (cpu == smp_processor_id())
+ return;
- if (!need_resched && !nrpolling && (task_cpu(p) != smp_processor_id()))
- smp_send_reschedule(task_cpu(p));
+ /* NEED_RESCHED must be visible before we test POLLING_NRFLAG */
+ smp_mb();
+ if (!test_tsk_thread_flag(p, TIF_POLLING_NRFLAG))
+ smp_send_reschedule(cpu);
}
#else
static inline void resched_task(task_t *p)
{
+ assert_spin_locked(&task_rq(p)->lock);
set_tsk_need_resched(p);
}
#endif
@@ -930,27 +994,61 @@ void kick_process(task_t *p)
* We want to under-estimate the load of migration sources, to
* balance conservatively.
*/
-static inline unsigned long source_load(int cpu, int type)
+static inline unsigned long __source_load(int cpu, int type, enum idle_type idle)
{
runqueue_t *rq = cpu_rq(cpu);
- unsigned long load_now = rq->nr_running * SCHED_LOAD_SCALE;
+ unsigned long running = rq->nr_running;
+ unsigned long source_load, cpu_load = rq->cpu_load[type-1],
+ load_now = running * SCHED_LOAD_SCALE;
+
if (type == 0)
- return load_now;
+ source_load = load_now;
+ else
+ source_load = min(cpu_load, load_now);
- return min(rq->cpu_load[type-1], load_now);
+ if (running > 1 || (idle == NOT_IDLE && running))
+ /*
+ * If we are busy rebalancing the load is biased by
+ * priority to create 'nice' support across cpus. When
+ * idle rebalancing we should only bias the source_load if
+ * there is more than one task running on that queue to
+ * prevent idle rebalance from trying to pull tasks from a
+ * queue with only one running task.
+ */
+ source_load = source_load * rq->prio_bias / running;
+
+ return source_load;
+}
+
+static inline unsigned long source_load(int cpu, int type)
+{
+ return __source_load(cpu, type, NOT_IDLE);
}
/*
* Return a high guess at the load of a migration-target cpu
*/
-static inline unsigned long target_load(int cpu, int type)
+static inline unsigned long __target_load(int cpu, int type, enum idle_type idle)
{
runqueue_t *rq = cpu_rq(cpu);
- unsigned long load_now = rq->nr_running * SCHED_LOAD_SCALE;
+ unsigned long running = rq->nr_running;
+ unsigned long target_load, cpu_load = rq->cpu_load[type-1],
+ load_now = running * SCHED_LOAD_SCALE;
+
if (type == 0)
- return load_now;
+ target_load = load_now;
+ else
+ target_load = max(cpu_load, load_now);
+
+ if (running > 1 || (idle == NOT_IDLE && running))
+ target_load = target_load * rq->prio_bias / running;
- return max(rq->cpu_load[type-1], load_now);
+ return target_load;
+}
+
+static inline unsigned long target_load(int cpu, int type)
+{
+ return __target_load(cpu, type, NOT_IDLE);
}
/*
@@ -1411,7 +1509,7 @@ void fastcall wake_up_new_task(task_t *p, unsigned long clone_flags)
list_add_tail(&p->run_list, &current->run_list);
p->array = current->array;
p->array->nr_active++;
- rq->nr_running++;
+ inc_nr_running(p, rq);
}
set_need_resched();
} else
@@ -1756,9 +1854,9 @@ void pull_task(runqueue_t *src_rq, prio_array_t *src_array, task_t *p,
runqueue_t *this_rq, prio_array_t *this_array, int this_cpu)
{
dequeue_task(p, src_array);
- src_rq->nr_running--;
+ dec_nr_running(p, src_rq);
set_task_cpu(p, this_cpu);
- this_rq->nr_running++;
+ inc_nr_running(p, this_rq);
enqueue_task(p, this_array);
p->timestamp = (p->timestamp - src_rq->timestamp_last_tick)
+ this_rq->timestamp_last_tick;
@@ -1937,9 +2035,9 @@ find_busiest_group(struct sched_domain *sd, int this_cpu,
/* Bias balancing toward cpus of our domain */
if (local_group)
- load = target_load(i, load_idx);
+ load = __target_load(i, load_idx, idle);
else
- load = source_load(i, load_idx);
+ load = __source_load(i, load_idx, idle);
avg_load += load;
}
@@ -2044,14 +2142,15 @@ out_balanced:
/*
* find_busiest_queue - find the busiest runqueue among the cpus in group.
*/
-static runqueue_t *find_busiest_queue(struct sched_group *group)
+static runqueue_t *find_busiest_queue(struct sched_group *group,
+ enum idle_type idle)
{
unsigned long load, max_load = 0;
runqueue_t *busiest = NULL;
int i;
for_each_cpu_mask(i, group->cpumask) {
- load = source_load(i, 0);
+ load = __source_load(i, 0, idle);
if (load > max_load) {
max_load = load;
@@ -2095,7 +2194,7 @@ static int load_balance(int this_cpu, runqueue_t *this_rq,
goto out_balanced;
}
- busiest = find_busiest_queue(group);
+ busiest = find_busiest_queue(group, idle);
if (!busiest) {
schedstat_inc(sd, lb_nobusyq[idle]);
goto out_balanced;
@@ -2218,7 +2317,7 @@ static int load_balance_newidle(int this_cpu, runqueue_t *this_rq,
goto out_balanced;
}
- busiest = find_busiest_queue(group);
+ busiest = find_busiest_queue(group, NEWLY_IDLE);
if (!busiest) {
schedstat_inc(sd, lb_nobusyq[NEWLY_IDLE]);
goto out_balanced;
@@ -3451,8 +3550,10 @@ void set_user_nice(task_t *p, long nice)
goto out_unlock;
}
array = p->array;
- if (array)
+ if (array) {
dequeue_task(p, array);
+ dec_prio_bias(rq, p->static_prio);
+ }
old_prio = p->prio;
new_prio = NICE_TO_PRIO(nice);
@@ -3462,6 +3563,7 @@ void set_user_nice(task_t *p, long nice)
if (array) {
enqueue_task(p, array);
+ inc_prio_bias(rq, p->static_prio);
/*
* If the task increased its priority or is running and
* lowered its priority, then reschedule its CPU:
generated by cgit v1.2.3 (git 2.25.1) at 2024-12-24 07:24:02 +0000