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-rw-r--r--kernel/sched.c26
1 files changed, 21 insertions, 5 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index b4dab63c6db..0ec84f57695 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1941,6 +1941,7 @@ int can_migrate_task(task_t *p, runqueue_t *rq, int this_cpu,
return 1;
}
+#define rq_best_prio(rq) min((rq)->curr->prio, (rq)->best_expired_prio)
/*
* move_tasks tries to move up to max_nr_move tasks and max_load_move weighted
* load from busiest to this_rq, as part of a balancing operation within
@@ -1955,7 +1956,9 @@ static int move_tasks(runqueue_t *this_rq, int this_cpu, runqueue_t *busiest,
{
prio_array_t *array, *dst_array;
struct list_head *head, *curr;
- int idx, pulled = 0, pinned = 0, this_min_prio;
+ int idx, pulled = 0, pinned = 0, this_best_prio, busiest_best_prio;
+ int busiest_best_prio_seen;
+ int skip_for_load; /* skip the task based on weighted load issues */
long rem_load_move;
task_t *tmp;
@@ -1964,7 +1967,16 @@ static int move_tasks(runqueue_t *this_rq, int this_cpu, runqueue_t *busiest,
rem_load_move = max_load_move;
pinned = 1;
- this_min_prio = this_rq->curr->prio;
+ this_best_prio = rq_best_prio(this_rq);
+ busiest_best_prio = rq_best_prio(busiest);
+ /*
+ * Enable handling of the case where there is more than one task
+ * with the best priority. If the current running task is one
+ * of those with prio==busiest_best_prio we know it won't be moved
+ * and therefore it's safe to override the skip (based on load) of
+ * any task we find with that prio.
+ */
+ busiest_best_prio_seen = busiest_best_prio == busiest->curr->prio;
/*
* We first consider expired tasks. Those will likely not be
@@ -2009,8 +2021,12 @@ skip_queue:
* skip a task if it will be the highest priority task (i.e. smallest
* prio value) on its new queue regardless of its load weight
*/
- if ((idx >= this_min_prio && tmp->load_weight > rem_load_move) ||
+ skip_for_load = tmp->load_weight > rem_load_move;
+ if (skip_for_load && idx < this_best_prio)
+ skip_for_load = !busiest_best_prio_seen && idx == busiest_best_prio;
+ if (skip_for_load ||
!can_migrate_task(tmp, busiest, this_cpu, sd, idle, &pinned)) {
+ busiest_best_prio_seen |= idx == busiest_best_prio;
if (curr != head)
goto skip_queue;
idx++;
@@ -2031,8 +2047,8 @@ skip_queue:
* and the prescribed amount of weighted load.
*/
if (pulled < max_nr_move && rem_load_move > 0) {
- if (idx < this_min_prio)
- this_min_prio = idx;
+ if (idx < this_best_prio)
+ this_best_prio = idx;
if (curr != head)
goto skip_queue;
idx++;