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sched: SCHED_HMP multi-domain task migration control

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We need a way to prevent tasks that are migrating up and down the
hmp_domains from migrating straight on through before the load has
adapted to the new compute capacity of the CPU on the new hmp_domain.
This patch adds a next up/down migration delay that prevents the task
from doing another migration in the same direction until the delay
has expired.

Signed-off-by: Morten Rasmussen <Morten.Rasmussen@arm.com>
This commit is contained in:
Morten Rasmussen 2012-09-14 14:38:17 +01:00 committed by Jon Medhurst
parent 0d811e649a
commit 76525733b4
3 changed files with 46 additions and 0 deletions
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4
include/linux/sched.h
View File

@ -938,6 +938,10 @@ struct sched_avg {
s64 decay_count;
unsigned long load_avg_contrib;
unsigned long load_avg_ratio;
#ifdef CONFIG_SCHED_HMP
u64 hmp_last_up_migration;
u64 hmp_last_down_migration;
#endif
u32 usage_avg_sum;
};

4
kernel/sched/core.c
View File

@ -1617,6 +1617,10 @@ static void __sched_fork(struct task_struct *p)
#if defined(CONFIG_SMP) && defined(CONFIG_FAIR_GROUP_SCHED)
p->se.avg.runnable_avg_period = 0;
p->se.avg.runnable_avg_sum = 0;
#ifdef CONFIG_SCHED_HMP
p->se.avg.hmp_last_up_migration = 0;
p->se.avg.hmp_last_down_migration = 0;
#endif
#endif
#ifdef CONFIG_SCHEDSTATS
memset(&p->se.statistics, 0, sizeof(p->se.statistics));

38
kernel/sched/fair.c
View File

@ -3401,12 +3401,16 @@ static int __init hmp_cpu_mask_setup(void)
* tweaking suit particular needs.
*
* hmp_up_prio: Only up migrate task with high priority (<hmp_up_prio)
* hmp_next_up_threshold: Delay before next up migration (1024 ~= 1 ms)
* hmp_next_down_threshold: Delay before next down migration (1024 ~= 1 ms)
*/
unsigned int hmp_up_threshold = 512;
unsigned int hmp_down_threshold = 256;
#ifdef CONFIG_SCHED_HMP_PRIO_FILTER
unsigned int hmp_up_prio = NICE_TO_PRIO(CONFIG_SCHED_HMP_PRIO_FILTER_VAL);
#endif
unsigned int hmp_next_up_threshold = 4096;
unsigned int hmp_next_down_threshold = 4096;
static unsigned int hmp_up_migration(int cpu, struct sched_entity *se);
static unsigned int hmp_down_migration(int cpu, struct sched_entity *se);
@ -3469,6 +3473,21 @@ static inline unsigned int hmp_select_slower_cpu(struct task_struct *tsk,
tsk_cpus_allowed(tsk));
}
static inline void hmp_next_up_delay(struct sched_entity *se, int cpu)
{
struct cfs_rq *cfs_rq = &cpu_rq(cpu)->cfs;
se->avg.hmp_last_up_migration = cfs_rq_clock_task(cfs_rq);
se->avg.hmp_last_down_migration = 0;
}
static inline void hmp_next_down_delay(struct sched_entity *se, int cpu)
{
struct cfs_rq *cfs_rq = &cpu_rq(cpu)->cfs;
se->avg.hmp_last_down_migration = cfs_rq_clock_task(cfs_rq);
se->avg.hmp_last_up_migration = 0;
}
#endif /* CONFIG_SCHED_HMP */
/*
@ -3572,11 +3591,13 @@ select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flags)
#ifdef CONFIG_SCHED_HMP
if (hmp_up_migration(prev_cpu, &p->se)) {
new_cpu = hmp_select_faster_cpu(p, prev_cpu);
hmp_next_up_delay(&p->se, new_cpu);
trace_sched_hmp_migrate(p, new_cpu, 0);
return new_cpu;
}
if (hmp_down_migration(prev_cpu, &p->se)) {
new_cpu = hmp_select_slower_cpu(p, prev_cpu);
hmp_next_down_delay(&p->se, new_cpu);
trace_sched_hmp_migrate(p, new_cpu, 0);
return new_cpu;
}
@ -5859,6 +5880,8 @@ static void nohz_idle_balance(int this_cpu, enum cpu_idle_type idle) { }
static unsigned int hmp_up_migration(int cpu, struct sched_entity *se)
{
struct task_struct *p = task_of(se);
struct cfs_rq *cfs_rq = &cpu_rq(cpu)->cfs;
u64 now;
if (hmp_cpu_is_fastest(cpu))
return 0;
@ -5869,6 +5892,12 @@ static unsigned int hmp_up_migration(int cpu, struct sched_entity *se)
return 0;
#endif
/* Let the task load settle before doing another up migration */
now = cfs_rq_clock_task(cfs_rq);
if (((now - se->avg.hmp_last_up_migration) >> 10)
< hmp_next_up_threshold)
return 0;
if (cpumask_intersects(&hmp_faster_domain(cpu)->cpus,
tsk_cpus_allowed(p))
&& se->avg.load_avg_ratio > hmp_up_threshold) {
@ -5881,6 +5910,8 @@ static unsigned int hmp_up_migration(int cpu, struct sched_entity *se)
static unsigned int hmp_down_migration(int cpu, struct sched_entity *se)
{
struct task_struct *p = task_of(se);
struct cfs_rq *cfs_rq = &cpu_rq(cpu)->cfs;
u64 now;
if (hmp_cpu_is_slowest(cpu))
return 0;
@ -5891,6 +5922,12 @@ static unsigned int hmp_down_migration(int cpu, struct sched_entity *se)
return 1;
#endif
/* Let the task load settle before doing another down migration */
now = cfs_rq_clock_task(cfs_rq);
if (((now - se->avg.hmp_last_down_migration) >> 10)
< hmp_next_down_threshold)
return 0;
if (cpumask_intersects(&hmp_slower_domain(cpu)->cpus,
tsk_cpus_allowed(p))
&& se->avg.load_avg_ratio < hmp_down_threshold) {
@ -6081,6 +6118,7 @@ static void hmp_force_up_migration(int this_cpu)
target->migrate_task = p;
force = 1;
trace_sched_hmp_migrate(p, target->push_cpu, 1);
hmp_next_up_delay(&p->se, target->push_cpu);
}
}
raw_spin_unlock_irqrestore(&target->lock, flags);