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SubjectRe: [patch v2 1/2] sched: check for prev_cpu == this_cpu before calling wake_affine()
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On Tue, 2010-04-20 at 01:55 -0700, Peter Zijlstra wrote:
> On Tue, 2010-04-20 at 10:46 +0200, Peter Zijlstra wrote:
> > So should we be using idle_cpu(i) instead?
>
> something like the below..

Looks good to me.

Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>

>
> ---
> Index: linux-2.6/kernel/sched_fair.c
> ===================================================================
> --- linux-2.6.orig/kernel/sched_fair.c
> +++ linux-2.6/kernel/sched_fair.c
> @@ -1375,26 +1375,25 @@ find_idlest_cpu(struct sched_group *grou
> /*
> * Try and locate an idle CPU in the sched_domain.
> */
> -static int
> -select_idle_sibling(struct task_struct *p, int target)
> +static int select_idle_sibling(struct task_struct *p, int target)
> {
> int cpu = smp_processor_id();
> int prev_cpu = task_cpu(p);
> - int i;
> struct sched_domain *sd;
> + int i;
>
> /*
> * If the task is going to be woken-up on this cpu and if it is
> * already idle, then it is the right target.
> */
> - if (target == cpu && !cpu_rq(cpu)->cfs.nr_running)
> + if (target == cpu && idle_cpu(cpu))
> return cpu;
>
> /*
> * If the task is going to be woken-up on the cpu where it previously
> * ran and if it is currently idle, then it the right target.
> */
> - if (target == prev_cpu && !cpu_rq(prev_cpu)->cfs.nr_running)
> + if (target == prev_cpu && idle_cpu(prev_cpu))
> return prev_cpu;
>
> /*
> @@ -1405,7 +1404,7 @@ select_idle_sibling(struct task_struct *
> break;
>
> for_each_cpu_and(i, sched_domain_span(sd), &p->cpus_allowed) {
> - if (!cpu_rq(i)->cfs.nr_running) {
> + if (idle_cpu(i)) {
> target = i;
> break;
> }
> @@ -1479,16 +1478,14 @@ select_task_rq_fair(struct rq *rq, struc
> want_sd = 0;
> }
>
> - if (want_affine) {
> - /*
> - * If both cpu and prev_cpu are part of this domain,
> - * cpu is a valid SD_WAKE_AFFINE target.
> - */
> - if (cpumask_test_cpu(prev_cpu, sched_domain_span(tmp))
> - && (tmp->flags & SD_WAKE_AFFINE)) {
> - affine_sd = tmp;
> - want_affine = 0;
> - }
> + /*
> + * If both cpu and prev_cpu are part of this domain,
> + * cpu is a valid SD_WAKE_AFFINE target.
> + */
> + if (want_affine && (tmp->flags & SD_WAKE_AFFINE) &&
> + cpumask_test_cpu(prev_cpu, sched_domain_span(tmp))) {
> + affine_sd = tmp;
> + want_affine = 0;
> }
>
> if (!want_sd && !want_affine)
>
>



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