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

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Message-ID: <1351045963.22024.12.camel@liguang.fnst.cn.fujitsu.com>
Date:	Wed, 24 Oct 2012 10:32:43 +0800
From:	li guang <lig.fnst@...fujitsu.com>
To:	Morten Rasmussen <Morten.Rasmussen@....com>
Cc:	Viresh Kumar <viresh.kumar@...aro.org>,
	"paulmck@...ux.vnet.ibm.com" <paulmck@...ux.vnet.ibm.com>,
	"pjt@...gle.com" <pjt@...gle.com>,
	"peterz@...radead.org" <peterz@...radead.org>,
	"suresh.b.siddha@...el.com" <suresh.b.siddha@...el.com>,
	"linaro-sched-sig@...ts.linaro.org" 
	<linaro-sched-sig@...ts.linaro.org>,
	"linaro-dev@...ts.linaro.org" <linaro-dev@...ts.linaro.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Amit Kucheria <amit.kucheria@...aro.org>,
	Arvind Chauhan <Arvind.Chauhan@....com>,
	Robin Randhawa <Robin.Randhawa@....com>
Subject: Re: [RFC PATCH 04/10] sched: Introduce priority-based task
 migration filter

在 2012-10-09二的 17:40 +0100，Morten Rasmussen写道：
> On Thu, Oct 04, 2012 at 07:27:00AM +0100, Viresh Kumar wrote:
> > 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;

hmp_*_threshold maybe sysctl_hmp_*_threshold,
and appear at /proc/sys/kernel,
so, can be adjusted to be rational.

> > > +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
> 
> --
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-- 
liguang    lig.fnst@...fujitsu.com
FNST linux kernel team

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