On 13/11/14 10:30, Wanpeng Li wrote:
Hi Juri,Oh, right, now it makes sense. Good catch! :)
On 11/13/14, 5:37 PM, Juri Lelli wrote:
not sure I understand what the problem is here.
On 11/11/14 01:52, Wanpeng Li wrote:
Queued ticks are scheduled to match the budget, which means the budget... enforce the budget? It means that when the budget is consumed the
is overall consumed and the dl task should be throttled.
task has to be throttled...
The parameter of task_tick_dl() queued == 1 means that hrtick is fired.Dl task willSo, the task that is going to preempt curr is picked by
be replenished immediately if fail to start a dl timer.
However, the curr maybe not the left most dl task in the rb tree any
more after this immediately replenished and reschedule is needed.
Start high-res preemption tick for this upcoming rescheduled dl task
is not correct.
pick_next_task_dl(), that correctly starts the hrtick for this new task.
Maybe you can add more information about what you are seeing? A callpath
hrtick() => task_tick_dl( , ,1), so p->dl.runtime should be <= 0 if
queued == 1. What I see is queued == 1 && p->dl.runtime > 0 && p is not
the left most task and hrtick is start for this task.
Could you please post a second version with a more explanatory changelog
and maybe a comment just above the check?
This patch fix it by not starting high-res preemption tick for a--
non-running dl task.
Signed-off-by: Wanpeng Li <wanpeng.li@xxxxxxxxxxxxxxx>
kernel/sched/deadline.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 56674f6..2a6a5bb 100644
@@ -1090,7 +1090,8 @@ static void task_tick_dl(struct rq *rq, struct task_struct *p, int queued)
- if (hrtick_enabled(rq) && queued && p->dl.runtime > 0)
+ if (hrtick_enabled(rq) && queued && p->dl.runtime > 0 &&
+ is_leftmost(p, &rq->dl))
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