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sched: Scale down cpu_power due to RT tasks

Browse source 
Keep an average on the amount of time spend on RT tasks and use
that fraction to scale down the cpu_power for regular tasks.

Signed-off-by: Peter Zijlstra <[email protected]>
Tested-by: Andreas Herrmann <[email protected]>
Acked-by: Andreas Herrmann <[email protected]>
Acked-by: Gautham R Shenoy <[email protected]>
Cc: Balbir Singh <[email protected]>
LKML-Reference: <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
This commit is contained in:
Peter Zijlstra 2009-09-01 10:34:37 +02:00 • committed by Ingo Molnar
commit e9e9250bc7
4 changed files with 72 additions and 7 deletions
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64
kernel/sched.c
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@ -627,6 +627,9 @@ struct rq {
struct task_struct *migration_thread;
struct list_head migration_queue;
u64 rt_avg;
u64 age_stamp;
#endif
/* calc_load related fields */
@ -862,6 +865,14 @@ unsigned int sysctl_sched_shares_ratelimit = 250000;
*/
unsigned int sysctl_sched_shares_thresh = 4;
/*
* period over which we average the RT time consumption, measured
* in ms.
*
* default: 1s
*/
const_debug unsigned int sysctl_sched_time_avg = MSEC_PER_SEC;
/*
* period over which we measure -rt task cpu usage in us.
* default: 1s
@ -1280,12 +1291,37 @@ void wake_up_idle_cpu(int cpu)
}
#endif /* CONFIG_NO_HZ */
static u64 sched_avg_period(void)
{
return (u64)sysctl_sched_time_avg * NSEC_PER_MSEC / 2;
}
static void sched_avg_update(struct rq *rq)
{
s64 period = sched_avg_period();
while ((s64)(rq->clock - rq->age_stamp) > period) {
rq->age_stamp += period;
rq->rt_avg /= 2;
}
}
static void sched_rt_avg_update(struct rq *rq, u64 rt_delta)
{
rq->rt_avg += rt_delta;
sched_avg_update(rq);
}
#else /* !CONFIG_SMP */
static void resched_task(struct task_struct *p)
{
assert_spin_locked(&task_rq(p)->lock);
set_tsk_need_resched(p);
}
static void sched_rt_avg_update(struct rq *rq, u64 rt_delta)
{
}
#endif /* CONFIG_SMP */
#if BITS_PER_LONG == 32
@ -3699,7 +3735,7 @@ static inline int check_power_save_busiest_group(struct sd_lb_stats *sds,
}
#endif /* CONFIG_SCHED_MC || CONFIG_SCHED_SMT */
unsigned long __weak arch_smt_gain(struct sched_domain *sd, int cpu)
unsigned long __weak arch_scale_smt_power(struct sched_domain *sd, int cpu)
{
unsigned long weight = cpumask_weight(sched_domain_span(sd));
unsigned long smt_gain = sd->smt_gain;
@ -3709,6 +3745,24 @@ unsigned long __weak arch_smt_gain(struct sched_domain *sd, int cpu)
return smt_gain;
}
unsigned long scale_rt_power(int cpu)
{
struct rq *rq = cpu_rq(cpu);
u64 total, available;
sched_avg_update(rq);
total = sched_avg_period() + (rq->clock - rq->age_stamp);
available = total - rq->rt_avg;
if (unlikely((s64)total < SCHED_LOAD_SCALE))
total = SCHED_LOAD_SCALE;
total >>= SCHED_LOAD_SHIFT;
return div_u64(available, total);
}
static void update_cpu_power(struct sched_domain *sd, int cpu)
{
unsigned long weight = cpumask_weight(sched_domain_span(sd));
@ -3719,11 +3773,15 @@ static void update_cpu_power(struct sched_domain *sd, int cpu)
/* here we could scale based on cpufreq */
if ((sd->flags & SD_SHARE_CPUPOWER) && weight > 1) {
power *= arch_smt_gain(sd, cpu);
power *= arch_scale_smt_power(sd, cpu);
power >>= SCHED_LOAD_SHIFT;
}
/* here we could scale based on RT time */
power *= scale_rt_power(cpu);
power >>= SCHED_LOAD_SHIFT;
if (!power)
power = 1;
if (power != old) {
sdg->__cpu_power = power;