Re: [PATCH V3] sched/deadline: Update rq_clock of later_rq when pushing a task

On Fri, Jul 20, 2018 at 02:46:15PM +0200, Peter Zijlstra wrote:

On Fri, Jul 20, 2018 at 11:16:30AM +0200, Daniel Bristot de Oliveira wrote:

...

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index fbfc3f1d368a..8b50eea4b607 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -2090,8 +2090,14 @@ static int push_dl_task(struct rq *rq) sub_rq_bw(&next_task->dl, &rq->dl); set_task_cpu(next_task, later_rq->cpu); add_rq_bw(&next_task->dl, &later_rq->dl);

• /*

• * Update the later_rq clock here, because the clock is used
  

• * by the cpufreq_update_util() inside __add_running_bw().
  

• */
  

• update_rq_clock(later_rq); add_running_bw(&next_task->dl, &later_rq->dl);

• activate_task(later_rq, next_task, 0);

• activate_task(later_rq, next_task, ENQUEUE_NOCLOCK); ret = 1;

resched_curr(later_rq);

Why isn't push_rt_task() affected by the very same issue?

Aah, I see, its the add_running_bw() think; for which RT doesn't have a counter-part.