linux-kernel - Re: [RFC PATCH 04/10] sched: Introduce priority-based task migration filter

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Message-ID: <CAKohpo=gvA4o=d3rw18O8sMOfXCh1M=39OcdOre4c4Azs42REg@mail.gmail.com>
Date:	Thu, 4 Oct 2012 11:57:00 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	morten.rasmussen@....com
Cc:	paulmck@...ux.vnet.ibm.com, pjt@...gle.com, peterz@...radead.org,
	suresh.b.siddha@...el.com, linaro-sched-sig@...ts.linaro.org,
	linaro-dev@...ts.linaro.org, linux-kernel@...r.kernel.org,
	Amit Kucheria <amit.kucheria@...aro.org>,
	Arvind.Chauhan@....com, Robin Randhawa <robin.randhawa@....com>
Subject: Re: [RFC PATCH 04/10] sched: Introduce priority-based task migration filter

On 22 September 2012 00:02,  <morten.rasmussen@....com> wrote:

> +config SCHED_HMP_PRIO_FILTER
> +       bool "(EXPERIMENTAL) Filter HMP migrations by task priority"
> +       depends on SCHED_HMP

Should it depend on EXPERIMENTAL?

> +       help
> +         Enables task priority based HMP migration filter. Any task with
> +         a NICE value above the threshold will always be on low-power cpus
> +         with less compute capacity.
> +
> +config SCHED_HMP_PRIO_FILTER_VAL
> +       int "NICE priority threshold"
> +       default 5
> +       depends on SCHED_HMP_PRIO_FILTER
> +
>  config HAVE_ARM_SCU
>         bool
>         help
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 490f1f0..8f0f3b9 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -3129,9 +3129,12 @@ static int __init hmp_cpu_mask_setup(void)
>   * hmp_down_threshold: max. load allowed for tasks migrating to a slower cpu
>   * The default values (512, 256) offer good responsiveness, but may need
>   * tweaking suit particular needs.
> + *
> + * hmp_up_prio: Only up migrate task with high priority (<hmp_up_prio)
>   */
>  unsigned int hmp_up_threshold = 512;
>  unsigned int hmp_down_threshold = 256;
> +unsigned int hmp_up_prio = NICE_TO_PRIO(CONFIG_SCHED_HMP_PRIO_FILTER_VAL);
>
>  static unsigned int hmp_up_migration(int cpu, struct sched_entity *se);
>  static unsigned int hmp_down_migration(int cpu, struct sched_entity *se);
> @@ -5491,6 +5494,12 @@ static unsigned int hmp_up_migration(int cpu, struct sched_entity *se)
>         if (hmp_cpu_is_fastest(cpu))
>                 return 0;
>
> +#ifdef CONFIG_SCHED_HMP_PRIO_FILTER
> +       /* Filter by task priority */
> +       if (p->prio >= hmp_up_prio)
> +               return 0;
> +#endif
> +
>         if (cpumask_intersects(&hmp_faster_domain(cpu)->cpus,
>                                         tsk_cpus_allowed(p))
>                 && se->avg.load_avg_ratio > hmp_up_threshold) {
> @@ -5507,6 +5516,12 @@ static unsigned int hmp_down_migration(int cpu, struct sched_entity *se)
>         if (hmp_cpu_is_slowest(cpu))
>                 return 0;
>
> +#ifdef CONFIG_SCHED_HMP_PRIO_FILTER
> +       /* Filter by task priority */
> +       if (p->prio >= hmp_up_prio)
> +               return 1;
> +#endif

Even if below cpumask_intersects() fails?

>         if (cpumask_intersects(&hmp_slower_domain(cpu)->cpus,
>                                         tsk_cpus_allowed(p))
>                 && se->avg.load_avg_ratio < hmp_down_threshold) {

--
viresh
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