On Fri, 2012-07-27 at 09:47 +0800, Alex Shi wrote:
> On 07/26/2012 05:37 PM, Mike Galbraith wrote:
>
> > On Thu, 2012-07-26 at 13:27 +0800, Alex Shi wrote:
> >
> >> if (affine_sd) {
> >> - if (cpu == prev_cpu || wake_affine(affine_sd, p, sync))
> >> + if (wake_affine(affine_sd, p, sync))
> >> prev_cpu = cpu;
> >>
> >> new_cpu = select_idle_sibling(p, prev_cpu);
> >
> > Hm, if cpu == prev_cpu, asking wake_affine() if it's ok to put wakee
> > back where it came from is wasted cycles.. that's where the task is
> > headed regardless of reply.
> >
> > -Mike
> >
>
>
>
>
> Sure. I modified the patch as below:
(dang, plain text can't make upside down ack;)
> ===
> From 610515185d8a98c14c7c339c25381bc96cd99d93 Mon Sep 17 00:00:00 2001
> From: Alex Shi <alex....@intel.com>
> Date: Thu, 26 Jul 2012 08:55:34 +0800
> Subject: [PATCH 1/3] sched: recover SD_WAKE_AFFINE in select_task_rq_fair and
> code clean up
>
> Since power saving code was removed from sched now, the implement
> code is out of service in this function, and even pollute other logical.
> like, 'want_sd' never has chance to be set '0', that remove the effect
> of SD_WAKE_AFFINE here.
>
> So, clean up the obsolete code and some other unnecessary code.
>
> Signed-off-by: Alex Shi <alex....@intel.com>
> ---
> kernel/sched/fair.c | 32 +++-----------------------------
> 1 files changed, 3 insertions(+), 29 deletions(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 22321db..53fd8db 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -2686,7 +2686,6 @@ select_task_rq_fair(struct task_struct *p, int sd_flag,
> int wake_flags)
> int prev_cpu = task_cpu(p);
> int new_cpu = cpu;
> int want_affine = 0;
> - int want_sd = 1;
> int sync = wake_flags & WF_SYNC;
>
> if (p->nr_cpus_allowed == 1)
> @@ -2704,48 +2703,23 @@ select_task_rq_fair(struct task_struct *p, int
> sd_flag, int wake_flags)
> continue;
>
> /*
> - * If power savings logic is enabled for a domain, see if we
> - * are not overloaded, if so, don't balance wider.
> - */
> - if (tmp->flags & (SD_PREFER_LOCAL)) {
> - unsigned long power = 0;
> - unsigned long nr_running = 0;
> - unsigned long capacity;
> - int i;
> -
> - for_each_cpu(i, sched_domain_span(tmp)) {
> - power += power_of(i);
> - nr_running += cpu_rq(i)->cfs.nr_running;
> - }
> -
> - capacity = DIV_ROUND_CLOSEST(power, SCHED_POWER_SCALE);
> -
> - if (nr_running < capacity)
> - want_sd = 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)
> break;
> + }
>
> if (!(tmp->flags & sd_flag))
> continue;
>
> - if (want_sd)
> - sd = tmp;
> + sd = tmp;
> }
>
> if (affine_sd) {
> - if (cpu == prev_cpu || wake_affine(affine_sd, p, sync))
> + if (cpu != prev_cpu && wake_affine(affine_sd, p, sync))
> prev_cpu = cpu;
>
> new_cpu = select_idle_sibling(p, prev_cpu);
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
