Commit 1b028abc authored by Michael J Wang's avatar Michael J Wang Committed by Ingo Molnar
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sched/rt: Improve pick_next_highest_task_rt()

Avoid extra work by continuing on to the next rt_rq if the highest
prio task in current rt_rq is the same priority as our candidate

More detailed explanation:  if next is not NULL, then we have found a
candidate task, and its priority is next->prio.  Now we are looking
for an even higher priority task in the other rt_rq's.  idx is the
highest priority in the current candidate rt_rq.  In the current 3.3
code, if idx is equal to next->prio, we would start scanning the tasks
in that rt_rq and replace the current candidate task with a task from
that rt_rq.  But the new task would only have a priority that is equal
to our previous candidate task, so we have not advanced our goal of
finding a higher prio task.  So we should avoid the extra work by
continuing on to the next rt_rq if idx is equal to next->prio.
Signed-off-by: default avatarMichael J Wang <>
Acked-by: default avatarSteven Rostedt <>
Reviewed-by: default avatarYong Zhang <>
Signed-off-by: default avatarPeter Zijlstra <>

Signed-off-by: default avatarIngo Molnar <>
parent 2baab4e9
......@@ -1428,7 +1428,7 @@ static struct task_struct *pick_next_highest_task_rt(struct rq *rq, int cpu)
if (idx >= MAX_RT_PRIO)
if (next && next->prio < idx)
if (next && next->prio <= idx)
list_for_each_entry(rt_se, array->queue + idx, run_list) {
struct task_struct *p;
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