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sched: Force the address order of each sched class descriptor

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In order to make a micro optimization in pick_next_task(), the order of the
sched class descriptor address must be in the same order as their priority
to each other. That is:

 &idle_sched_class < &fair_sched_class < &rt_sched_class <
 &dl_sched_class < &stop_sched_class

In order to guarantee this order of the sched class descriptors, add each
one into their own data section and force the order in the linker script.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/157675913272.349305.8936736338884044103.stgit@localhost.localdomain
This commit is contained in:
Steven Rostedt (VMware)
2019-12-19 16:44:52 -05:00
committed by Peter Zijlstra
parent 87e867b426
commit 590d697963
6 changed files with 23 additions and 5 deletions
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3
kernel/sched/rt.c
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@@ -2429,7 +2429,8 @@ static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task)
return 0;
}
const struct sched_class rt_sched_class = {
const struct sched_class rt_sched_class
__attribute__((section("__rt_sched_class"))) = {
.next = &fair_sched_class,
.enqueue_task = enqueue_task_rt,
.dequeue_task = dequeue_task_rt,