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

On Thu, Oct 04, 2012 at 07:27:00AM +0100, Viresh Kumar wrote:

On 22 September 2012 00:02, morten.rasmussen@arm.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?

No. Good catch :)

...

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

-- viresh

Thanks, Morten