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sched/deadline: Fix confusing comments about selection of top pi-waiter 

This comment in the code is incomplete, and I believe it begs a definition of
dl_boosted to make sense of the condition that follows. Rewrite the comment and
also rearrange the condition that follows to reflect the first condition "we
have a top pi-waiter which is a SCHED_DEADLINE task" in that order. Also fix a
typo that follows.

Signed-off-by: Joel Fernandes <joelaf@google.com>
Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Acked-by: Juri Lelli <juri.lelli@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170713022429.10307-1-joelaf@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Joel Fernandes 2017-07-12 19:24:29 -07:00 committed by Ingo Molnar
parent 0e4097c335
commit 193be41e33
1 changed files with 8 additions and 6 deletions
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14
kernel/sched/deadline.c
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@ -1392,17 +1392,19 @@ static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags)
struct sched_dl_entity *pi_se = &p->dl;
/*
* Use the scheduling parameters of the top pi-waiter
* task if we have one and its (absolute) deadline is
* smaller than our one... OTW we keep our runtime and
* deadline.
* Use the scheduling parameters of the top pi-waiter task if:
* - we have a top pi-waiter which is a SCHED_DEADLINE task AND
* - our dl_boosted is set (i.e. the pi-waiter's (absolute) deadline is
* smaller than our deadline OR we are a !SCHED_DEADLINE task getting
* boosted due to a SCHED_DEADLINE pi-waiter).
* Otherwise we keep our runtime and deadline.
*/
if (pi_task && p->dl.dl_boosted && dl_prio(pi_task->normal_prio)) {
if (pi_task && dl_prio(pi_task->normal_prio) && p->dl.dl_boosted) {
pi_se = &pi_task->dl;
} else if (!dl_prio(p->normal_prio)) {
/*
* Special case in which we have a !SCHED_DEADLINE task
* that is going to be deboosted, but exceedes its
* that is going to be deboosted, but exceeds its
* runtime while doing so. No point in replenishing
* it, as it's going to return back to its original
* scheduling class after this.