Messages in this thread | | | Date | Fri, 24 Jul 2020 09:14:26 +0200 | From | Juri Lelli <> | Subject | Re: [PATCH] sched/deadline: dome some cleanup for push_dl_task() |
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Hi,
On 07/07/20 00:04, Peng Liu wrote: > 'commit 840d719604b0 ("sched/deadline: Update rq_clock of later_rq when pushing a task")' > introduced the update_rq_clock() to fix the "used-before-update" bug. > > 'commit f4904815f97a ("sched/deadline: Fix double accounting of rq/running bw in push & pull")' > took away the bug source(add_running_bw()). > > We no longer need to update rq_clock in advance, let activate_task() > worry about that. > > Signed-off-by: Peng Liu <iwtbavbm@gmail.com> > --- > kernel/sched/deadline.c | 8 +------- > 1 file changed, 1 insertion(+), 7 deletions(-) > > diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c > index 504d2f51b0d6..c3fa11f84d93 100644 > --- a/kernel/sched/deadline.c > +++ b/kernel/sched/deadline.c > @@ -2104,13 +2104,7 @@ static int push_dl_task(struct rq *rq) > > deactivate_task(rq, next_task, 0); > set_task_cpu(next_task, later_rq->cpu); > - > - /* > - * 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); > - activate_task(later_rq, next_task, ENQUEUE_NOCLOCK); > + activate_task(later_rq, next_task, 0); > ret = 1;
The change looks good to me, since now add_running_bw() is called later by enqueue_task_dl(), but rq_clock has already been updated by core's enqueue_task().
Daniel, Dietmar, a second pair of eyes (since you authored the commits above)?
I'd chage subject to something like "sched/deadline: Stop updating rq_clock before pushing a task".
Thanks,
Juri
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