Messages in this thread Patch in this message | | | Date | Fri, 26 Aug 2022 20:46:12 +0200 | Subject | Re: [PATCH v7 2/2] sched/rt: Trying to push current task when target disable migrating | From | Dietmar Eggemann <> |
| |
On 13/07/2022 15:48, Schspa Shi wrote: > When the task to push disable migration, retry to push the current > running task on this CPU away, instead doing nothing for this migrate > disabled task. > > Signed-off-by: Schspa Shi <schspa@gmail.com>
Unfortunately, I can't recreate this issue on my Arm64 6 CPUs system on mainline or PREEMPT_RT (linux-5.19.y-rt and v5.10.59-rt52) (the one you mentioned in v6.)
With an rt-app rt workload of 12-18 periodic rt-tasks (4/16ms) all with different priorities I never ran into a `is_migration_disabled(task)` situation. I only ever get `task_rq(task) != rq` or `task_running(rq, task)` under the `if (double_lock_balance(rq, lowest_rq))` condition in find_lock_lowest_rq().
[...]
> // XXX validate p is still the highest prio task > if (task_rq(p) == rq) { > diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c > index cb3b886a081c..21af20445e7f 100644 > --- a/kernel/sched/deadline.c > +++ b/kernel/sched/deadline.c > @@ -2335,6 +2335,15 @@ static int push_dl_task(struct rq *rq) > */ > task = pick_next_pushable_dl_task(rq); > if (task == next_task) { > + /* > + * If next task has now disabled migrating, see if we > + * can push the current task. > + */ > + if (unlikely(is_migration_disabled(task))) { > + put_task_struct(next_task); > + goto retry; > + } > +
Looks like for DL this makes no sense since we're not pushing rq->curr in `retry:` like for RT in case `is_migration_disabled(next_task)`.
[...]
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
| |