Messages in this thread | | | Date | Wed, 18 May 2011 10:31:53 +0800 | Subject | Re: [PATCH] sched: correct how RT task is picked | From | Yong Zhang <> |
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On Wed, May 18, 2011 at 9:38 AM, Steven Rostedt <rostedt@goodmis.org> wrote: >> I think you can take a look at next_prio(), it just calculate the >> next highest task on the current cpu; in this case, >> cpumask_test_cpu(cpu, &p->cpus_allowed) will be true for the most >> of time, but maybe that task is bound to this cpu. > > I've been looking at the history here, and I think that '-1' is a relic. > > If you look at sched_rt.c in f65eda4f789168ba5ff3fa75546c29efeed19f58: > > $ git show f65eda4f:kernel/sched_rt.c > > You'll see that push_rt_task calls pick_next_highest_task_rt() with a > -1. That code has long been replaced.
Yeah, the condition "cpu < 0" could be removed since we have no that kind of caller.
> > I'm a bit nervous about taking Hillf's patch as is. But a little more > reviewing and testing may prove that it is legit.
But another point is like I said before: 'cpumask_test_cpu(cpu, &p->cpus_allowed)' doesn't equal to 'p->rt.nr_cpus_allowed > 1' because we could have bounded task. So the condition 'if (cpumask_test_cpu(cpu, &p->cpus_allowed))' in Hillf's patch is not sufficient.
Thanks, Yong
-- Only stand for myself
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