Messages in this thread | | | Date | Tue, 12 Jul 2022 10:29:53 -0400 | From | Steven Rostedt <> | Subject | Re: [PATCH v5 2/2] sched/rt: Trying to push current task when target disable migrating |
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On Tue, 12 Jul 2022 09:31:25 +0800 Schspa Shi <schspa@gmail.com> 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> > --- > kernel/sched/core.c | 6 +++++- > kernel/sched/rt.c | 6 ++++++ > 2 files changed, 11 insertions(+), 1 deletion(-) > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index da0bf6fe9ecdc..0b1fefd97d874 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -2509,8 +2509,12 @@ int push_cpu_stop(void *arg) > if (p->sched_class->find_lock_rq) > lowest_rq = p->sched_class->find_lock_rq(p, rq); > > - if (!lowest_rq) > + if (!lowest_rq) {
Probably should add a comment reminding us that the find_lock() function above could have released the rq lock and allow p to schedule and be preempted again, and that lowest_rq could be NULL because p now has the migrate_disable flag set and not because it could not find the lowest rq.
-- Steve
> + if (unlikely(is_migration_disabled(p))) > + p->migration_flags |= MDF_PUSH; > + > goto out_unlock; > + } > > // XXX validate p is still the highest prio task > if (task_rq(p) == rq) { > diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c > index 7c32ba51b6d85..877380e465b7a 100644 > --- a/kernel/sched/rt.c > +++ b/kernel/sched/rt.c > @@ -2136,6 +2136,12 @@ static int push_rt_task(struct rq *rq, bool pull) > */ > task = pick_next_pushable_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))) > + goto retry; > /* > * The task hasn't migrated, and is still the next > * eligible task, but we failed to find a run-queue
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