Messages in this thread | | | Subject | Re: [PATCH]sched/rt: Do not try to push tasks if pinned task switches to RT | From | Steven Rostedt <> | Date | Tue, 29 Jan 2013 08:26:00 -0500 |
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On Tue, 2013-01-29 at 00:23 +0400, Kirill Tkhai wrote: > Just switched pinned task is not able to be pushed. If the rq had had > several RT tasks before they have already been considered as candidates > to be pushed (or pulled).
Thanks, but I have one minor nit.
> > Signed-off-by: Kirill V Tkhai <tkhai@yandex.ru> > CC: Steven Rostedt <rostedt@goodmis.org> > CC: Ingo Molnar <mingo@kernel.org> > CC: Peter Zijlstra <peterz@infradead.org> > CC: linux-rt-users <linux-rt-users@vger.kernel.org> > --- > kernel/sched/rt.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c > index 4e8f0f4..5f7d92b 100644 > --- a/kernel/sched/rt.c > +++ b/kernel/sched/rt.c > @@ -1925,9 +1925,9 @@ static void switched_to_rt(struct rq *rq, struct task_struct *p) > */ > if (p->on_rq && rq->curr != p) { > #ifdef CONFIG_SMP > - if (rq->rt.overloaded && push_rt_task(rq) && > + if (rq->rt.overloaded && p->nr_cpus_allowed > 1 &&
I would swap the order here. That is, check p->nr_cpus_allowed before rq->rt.overloaded. The order doesn't really matter, and even though rq->rt.overloaded is probably more likely to be 0, it is used by other CPUs. And as a micro-optimization, I rather read something that is used by only one CPU than to read something that may be modified by many CPUs.
-- Steve
> /* Don't resched if we changed runqueues */ > - rq != task_rq(p)) > + push_rt_task(rq) && rq != task_rq(p)) > check_resched = 0; > #endif /* CONFIG_SMP */ > if (check_resched && p->prio < rq->curr->prio)
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