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Commit e9e9250b authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

sched: Scale down cpu_power due to RT tasks 



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: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Tested-by: default avatarAndreas Herrmann <andreas.herrmann3@amd.com>
Acked-by: default avatarAndreas Herrmann <andreas.herrmann3@amd.com>
Acked-by: default avatarGautham R Shenoy <ego@in.ibm.com>
Cc: Balbir Singh <balbir@in.ibm.com>
LKML-Reference: <20090901083826.287778431@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent ab29230e

include/linux/sched.h

+1 −0
Original line number Diff line number Diff line
@@ -1831,6 +1831,7 @@ extern unsigned int sysctl_sched_child_runs_first; 
extern unsigned int sysctl_sched_features;

extern unsigned int sysctl_sched_migration_cost;

extern unsigned int sysctl_sched_nr_migrate;

extern unsigned int sysctl_sched_time_avg;

extern unsigned int sysctl_timer_migration;



int sched_nr_latency_handler(struct ctl_table *table, int write,

kernel/sched.c

+61 −3
Original line number Diff line number Diff line
@@ -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;

kernel/sched_rt.c

+2 −4
Original line number Diff line number Diff line
@@ -615,6 +615,8 @@ static void update_curr_rt(struct rq *rq) 
	curr->se.exec_start = rq->clock;

	cpuacct_charge(curr, delta_exec);



	sched_rt_avg_update(rq, delta_exec);



	if (!rt_bandwidth_enabled())

		return;
@@ -887,8 +889,6 @@ static void enqueue_task_rt(struct rq *rq, struct task_struct *p, int wakeup) 


	if (!task_current(rq, p) && p->rt.nr_cpus_allowed > 1)

		enqueue_pushable_task(rq, p);



	inc_cpu_load(rq, p->se.load.weight);

}



static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int sleep)
@@ -899,8 +899,6 @@ static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int sleep) 
	dequeue_rt_entity(rt_se);



	dequeue_pushable_task(rq, p);



	dec_cpu_load(rq, p->se.load.weight);

}



/*

kernel/sysctl.c

+8 −0
Original line number Diff line number Diff line
@@ -330,6 +330,14 @@ static struct ctl_table kern_table[] = { 
		.mode		= 0644,

		.proc_handler	= &proc_dointvec,

	},

	{

		.ctl_name	= CTL_UNNUMBERED,

		.procname	= "sched_time_avg",

		.data		= &sysctl_sched_time_avg,

		.maxlen		= sizeof(unsigned int),

		.mode		= 0644,

		.proc_handler	= &proc_dointvec,

	},

	{

		.ctl_name	= CTL_UNNUMBERED,

		.procname	= "timer_migration",