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SubjectRe: Patch "sched: Give CPU bound RT tasks preference" has been added to the 2.6.32-longterm tree
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On Tue, 2011-02-15 at 13:17 -0800, gregkh@suse.de wrote:
> This is a note to let you know that I've just added the patch titled
>
> sched: Give CPU bound RT tasks preference
>
> to the 2.6.32-longterm tree which can be found at:
> http://www.kernel.org/git/?p=linux/kernel/git/longterm/longterm-queue-2.6.32.git;a=summary
>
> The filename of the patch is:
> 0006-sched-Give-CPU-bound-RT-tasks-preference.patch
> and it can be found in the queue-2.6.32 subdirectory.
>
> If you, or anyone else, feels it should not be added to the 2.6.32 longterm tree,
> please let <stable@kernel.org> know about it.
>
>

I don't mind this patch being added to the long term tree. But I'm
curious about what is the criteria for adding changes to it? This is a
performance improvement and not a critical bug fix.

-- Steve

> >From 10db390cadda977081a7a34f60b8ce62557521c9 Mon Sep 17 00:00:00 2001
> From: stable-bot for Steven Rostedt <srostedt@redhat.com>
> Date: Thu, 10 Feb 2011 10:21:08 +0100
> Subject: sched: Give CPU bound RT tasks preference
>
> From:: Steven Rostedt <srostedt@redhat.com>
>
> Commit: b3bc211cfe7d5fe94b310480d78e00bea96fbf2a upstream
>
> If a high priority task is waking up on a CPU that is running a
> lower priority task that is bound to a CPU, see if we can move the
> high RT task to another CPU first. Note, if all other CPUs are
> running higher priority tasks than the CPU bounded current task,
> then it will be preempted regardless.
>
> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Cc: Gregory Haskins <ghaskins@novell.com>
> LKML-Reference: <20100921024138.888922071@goodmis.org>
> Signed-off-by: Ingo Molnar <mingo@elte.hu>
> Signed-off-by: Mike Galbraith <efault@gmx.de>
> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
> ---
> kernel/sched_rt.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> --- a/kernel/sched_rt.c
> +++ b/kernel/sched_rt.c
> @@ -965,7 +965,8 @@ select_task_rq_rt(struct rq *rq, struct
> * For equal prio tasks, we just let the scheduler sort it out.
> */
> if (unlikely(rt_task(rq->curr)) &&
> - rq->curr->prio < p->prio &&
> + (rq->curr->rt.nr_cpus_allowed < 2 ||
> + rq->curr->prio < p->prio) &&
> (p->rt.nr_cpus_allowed > 1)) {
> int cpu = find_lowest_rq(p);
>
> @@ -1493,9 +1494,10 @@ static void task_woken_rt(struct rq *rq,
> if (!task_running(rq, p) &&
> !test_tsk_need_resched(rq->curr) &&
> has_pushable_tasks(rq) &&
> + p->rt.nr_cpus_allowed > 1 &&
> rt_task(rq->curr) &&
> - rq->curr->prio < p->prio &&
> - p->rt.nr_cpus_allowed > 1)
> + (rq->curr->rt.nr_cpus_allowed < 2 ||
> + rq->curr->prio < p->prio))
> push_rt_tasks(rq);
> }
>
>
>
> Patches currently in longterm-queue-2.6.32 which might be from srostedt@redhat.com are




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