Messages in this thread Patch in this message | | | Date | Tue, 23 Feb 2016 13:28:22 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH] sched/deadline: Always calculate end of period on sched_yield() |
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On Fri, Feb 12, 2016 at 06:10:20PM -0500, Steven Rostedt wrote: > diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c > index cd64c979d0e1..1dd180cda574 100644 > --- a/kernel/sched/deadline.c > +++ b/kernel/sched/deadline.c > @@ -735,7 +735,7 @@ static void update_curr_dl(struct rq *rq) > * approach need further study. > */ > delta_exec = rq_clock_task(rq) - curr->se.exec_start; > - if (unlikely((s64)delta_exec <= 0)) > + if (unlikely((s64)delta_exec <= 0 && !dl_se->dl_yielded)) > return; > > schedstat_set(curr->se.statistics.exec_max,
Would something like this make sense instead?
It also retains the ->runtime while yielded, and would actually 'fix' a case where, when we call yield, we would have had a negative runtime after update_curr_dl().
The current code will 'gift' us extra runtime in that case.
--- kernel/sched/deadline.c | 20 +++++++++++++------- 1 file changed, 13 insertions(+), 7 deletions(-)
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index 57b939c81bce..c2bca80d3388 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -399,6 +399,9 @@ static void replenish_dl_entity(struct sched_dl_entity *dl_se, dl_se->runtime = pi_se->dl_runtime; } + if (dl_se->dl_yielded && dl_se->runtime > 0) + dl_se->runtime = 0; + /* * We keep moving the deadline away until we get some * available runtime for the entity. This ensures correct @@ -735,8 +738,11 @@ static void update_curr_dl(struct rq *rq) * approach need further study. */ delta_exec = rq_clock_task(rq) - curr->se.exec_start; - if (unlikely((s64)delta_exec <= 0)) + if (unlikely((s64)delta_exec <= 0)) { + if (unlikely(dl_se->dl_yielded)) + goto throttle; return; + } schedstat_set(curr->se.statistics.exec_max, max(curr->se.statistics.exec_max, delta_exec)); @@ -749,8 +755,10 @@ static void update_curr_dl(struct rq *rq) sched_rt_avg_update(rq, delta_exec); - dl_se->runtime -= dl_se->dl_yielded ? 0 : delta_exec; - if (dl_runtime_exceeded(dl_se)) { + dl_se->runtime -= delta_exec; + +throttle: + if (dl_runtime_exceeded(dl_se) || dl_se->dl_yielded) { dl_se->dl_throttled = 1; __dequeue_task_dl(rq, curr, 0); if (unlikely(dl_se->dl_boosted || !start_dl_timer(curr))) @@ -1002,10 +1010,8 @@ static void yield_task_dl(struct rq *rq) * it and the bandwidth timer will wake it up and will give it * new scheduling parameters (thanks to dl_yielded=1). */ - if (p->dl.runtime > 0) { - rq->curr->dl.dl_yielded = 1; - p->dl.runtime = 0; - } + rq->curr->dl.dl_yielded = 1; + update_rq_clock(rq); update_curr_dl(rq); /*
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