On Wed, 12 Mar 2014, Steven Rostedt wrote:
> Peter,
>
> I'm going through my inbox (over a year old), and found this patch from
> Kirill. It looks fine to me. You can apply it with my
>
> Acked-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
>
> -- Steve
>
> [PATCH]sched/rt: Do not try to push tasks if pinned task switches to RT
>
> 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).
>
> Signed-off-by: Kirill V Tkhai <tkhai@xxxxxxxxx>
> CC: Steven Rostedt <rostedt@xxxxxxxxxxx>
> CC: Ingo Molnar <mingo@xxxxxxxxxx>
> CC: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> CC: linux-rt-users <linux-rt-users@xxxxxxxxxxxxxxx>
> ---
> kernel/sched/rt.c | 4 ++--
> 1 files changed, 2 insertions(+), 2 deletions(-)
> diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
> index 4e8f0f4..5aab032 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 (p->nr_cpus_allowed > 1 && rq->rt.overloaded &&
> /* 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)
would there not need to be a check for p->migrate_disable ?
push_rt_task() is not checking and so a high prio RT task
preemting a low prio RT task in a migrate_disable() section
would actually push it off this cpu ? atleast I did not
find why that would not happen.
thx!
hofrat
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