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authorJuri Lelli <juri.lelli@gmail.com>2014-04-15 13:49:04 +0200
committerIngo Molnar <mingo@kernel.org>2014-05-07 11:51:31 +0200
commit5bfd126e80dca70431aef8fdbc1cf14535f3c338 (patch)
tree7f1988050d32bcab50468b0bf4afb2556b638d68 /kernel
parent2d513868e2a33e1d5315490ef4c861ee65babd65 (diff)
downloadlinux-5bfd126e80dca70431aef8fdbc1cf14535f3c338.tar.bz2
sched/deadline: Fix sched_yield() behavior
yield_task_dl() is broken: o it forces current to be throttled setting its runtime to zero; o it sets current's dl_se->dl_new to one, expecting that dl_task_timer() will queue it back with proper parameters at replenish time. Unfortunately, dl_task_timer() has this check at the very beginning: if (!dl_task(p) || dl_se->dl_new) goto unlock; So, it just bails out and the task is never replenished. It actually yielded forever. To fix this, introduce a new flag indicating that the task properly yielded the CPU before its current runtime expired. While this is a little overdoing at the moment, the flag would be useful in the future to discriminate between "good" jobs (of which remaining runtime could be reclaimed, i.e. recycled) and "bad" jobs (for which dl_throttled task has been set) that needed to be stopped. Reported-by: yjay.kim <yjay.kim@lge.com> Signed-off-by: Juri Lelli <juri.lelli@gmail.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20140429103953.e68eba1b2ac3309214e3dc5a@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched/core.c1
-rw-r--r--kernel/sched/deadline.c5
2 files changed, 4 insertions, 2 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 9fe2190005cb..e62c65a12d5b 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3124,6 +3124,7 @@ __setparam_dl(struct task_struct *p, const struct sched_attr *attr)
dl_se->dl_bw = to_ratio(dl_se->dl_period, dl_se->dl_runtime);
dl_se->dl_throttled = 0;
dl_se->dl_new = 1;
+ dl_se->dl_yielded = 0;
}
static void __setscheduler_params(struct task_struct *p,
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index b08095786cb8..800e99b99075 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -528,6 +528,7 @@ static enum hrtimer_restart dl_task_timer(struct hrtimer *timer)
sched_clock_tick();
update_rq_clock(rq);
dl_se->dl_throttled = 0;
+ dl_se->dl_yielded = 0;
if (p->on_rq) {
enqueue_task_dl(rq, p, ENQUEUE_REPLENISH);
if (task_has_dl_policy(rq->curr))
@@ -893,10 +894,10 @@ static void yield_task_dl(struct rq *rq)
* We make the task go to sleep until its current deadline by
* forcing its runtime to zero. This way, update_curr_dl() stops
* it and the bandwidth timer will wake it up and will give it
- * new scheduling parameters (thanks to dl_new=1).
+ * new scheduling parameters (thanks to dl_yielded=1).
*/
if (p->dl.runtime > 0) {
- rq->curr->dl.dl_new = 1;
+ rq->curr->dl.dl_yielded = 1;
p->dl.runtime = 0;
}
update_curr_dl(rq);