Messages in this thread Patch in this message | | | Date | Thu, 13 Nov 2014 18:30:05 +0800 | From | Wanpeng Li <> | Subject | Re: [PATCH 2/2] sched/deadline: fix start high-res preemption tick for a non-running task |
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Hi Juri, On 11/13/14, 5:37 PM, Juri Lelli wrote: > Hi, > > 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 >> is overall consumed and the dl task should be throttled. > ... enforce the budget? It means that when the budget is consumed the > task has to be throttled...
Agreed.
> >> Dl task will >> 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. >> > So, the task that is going to preempt curr is picked by > 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 > maybe?
The parameter of task_tick_dl() queued == 1 means that hrtick is fired. 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.
Regards, Wanpeng Li
> > Thanks, > > - Juri > >> This patch fix it by not starting high-res preemption tick for a >> non-running dl task. >> >> Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com> >> --- >> 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 >> --- a/kernel/sched/deadline.c >> +++ b/kernel/sched/deadline.c >> @@ -1090,7 +1090,8 @@ static void task_tick_dl(struct rq *rq, struct task_struct *p, int queued) >> { >> update_curr_dl(rq); >> >> - if (hrtick_enabled(rq) && queued && p->dl.runtime > 0) >> + if (hrtick_enabled(rq) && queued && p->dl.runtime > 0 && >> + is_leftmost(p, &rq->dl)) >> start_hrtick_dl(rq, p); >> } >> >> > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/
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