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Commit cc367732 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

sched: debug, improve migration statistics 



add new migration statistics when SCHED_DEBUG and SCHEDSTATS
is enabled. Available in /proc/<PID>/sched.

Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 2d92f227

include/linux/sched.h

+18 −0
Original line number Diff line number Diff line
@@ -931,6 +931,24 @@ struct sched_entity { 
	u64			block_max;

	u64			exec_max;

	u64			slice_max;



	u64			nr_migrations;

	u64			nr_migrations_cold;

	u64			nr_failed_migrations_affine;

	u64			nr_failed_migrations_running;

	u64			nr_failed_migrations_hot;

	u64			nr_forced_migrations;

	u64			nr_forced2_migrations;



	u64			nr_wakeups;

	u64			nr_wakeups_sync;

	u64			nr_wakeups_migrate;

	u64			nr_wakeups_local;

	u64			nr_wakeups_remote;

	u64			nr_wakeups_affine;

	u64			nr_wakeups_affine_attempts;

	u64			nr_wakeups_passive;

	u64			nr_wakeups_idle;

#endif



#ifdef CONFIG_FAIR_GROUP_SCHED

kernel/sched.c

+54 −22
Original line number Diff line number Diff line
@@ -1005,6 +1005,23 @@ static inline void __set_task_cpu(struct task_struct *p, unsigned int cpu) 


#ifdef CONFIG_SMP



/*

 * Is this task likely cache-hot:

 */

static inline int

task_hot(struct task_struct *p, u64 now, struct sched_domain *sd)

{

	s64 delta;



	if (p->sched_class != &fair_sched_class)

		return 0;



	delta = now - p->se.exec_start;



	return delta < (s64)sysctl_sched_migration_cost;

}





void set_task_cpu(struct task_struct *p, unsigned int new_cpu)

{

	int old_cpu = task_cpu(p);
@@ -1022,6 +1039,11 @@ void set_task_cpu(struct task_struct *p, unsigned int new_cpu) 
		p->se.sleep_start -= clock_offset;

	if (p->se.block_start)

		p->se.block_start -= clock_offset;

	if (old_cpu != new_cpu) {

		schedstat_inc(p, se.nr_migrations);

		if (task_hot(p, old_rq->clock, NULL))

			schedstat_inc(p, se.nr_forced2_migrations);

	}

#endif

	p->se.vruntime -= old_cfsrq->min_vruntime -

					 new_cfsrq->min_vruntime;
@@ -1394,9 +1416,14 @@ static int wake_idle(int cpu, struct task_struct *p) 
		if (sd->flags & SD_WAKE_IDLE) {

			cpus_and(tmp, sd->span, p->cpus_allowed);

			for_each_cpu_mask(i, tmp) {

				if (idle_cpu(i))

				if (idle_cpu(i)) {

					if (i != task_cpu(p)) {

						schedstat_inc(p,

							se.nr_wakeups_idle);

					}

					return i;

				}

			}

		} else {

			break;

		}
@@ -1426,7 +1453,7 @@ static inline int wake_idle(int cpu, struct task_struct *p) 
 */

static int try_to_wake_up(struct task_struct *p, unsigned int state, int sync)

{

	int cpu, this_cpu, success = 0;

	int cpu, orig_cpu, this_cpu, success = 0;

	unsigned long flags;

	long old_state;

	struct rq *rq;
@@ -1445,6 +1472,7 @@ static int try_to_wake_up(struct task_struct *p, unsigned int state, int sync) 
		goto out_running;



	cpu = task_cpu(p);

	orig_cpu = cpu;

	this_cpu = smp_processor_id();



#ifdef CONFIG_SMP
@@ -1488,6 +1516,7 @@ static int try_to_wake_up(struct task_struct *p, unsigned int state, int sync) 
			unsigned long tl = this_load;

			unsigned long tl_per_task;



			schedstat_inc(p, se.nr_wakeups_affine_attempts);

			tl_per_task = cpu_avg_load_per_task(this_cpu);



			/*
@@ -1507,6 +1536,7 @@ static int try_to_wake_up(struct task_struct *p, unsigned int state, int sync) 
				 * there is no bad imbalance.

				 */

				schedstat_inc(this_sd, ttwu_move_affine);

				schedstat_inc(p, se.nr_wakeups_affine);

				goto out_set_cpu;

			}

		}
@@ -1518,6 +1548,7 @@ static int try_to_wake_up(struct task_struct *p, unsigned int state, int sync) 
		if (this_sd->flags & SD_WAKE_BALANCE) {

			if (imbalance*this_load <= 100*load) {

				schedstat_inc(this_sd, ttwu_move_balance);

				schedstat_inc(p, se.nr_wakeups_passive);

				goto out_set_cpu;

			}

		}
@@ -1543,6 +1574,15 @@ out_set_cpu: 


out_activate:

#endif /* CONFIG_SMP */

	schedstat_inc(p, se.nr_wakeups);

	if (sync)

		schedstat_inc(p, se.nr_wakeups_sync);

	if (orig_cpu != cpu)

		schedstat_inc(p, se.nr_wakeups_migrate);

	if (cpu == this_cpu)

		schedstat_inc(p, se.nr_wakeups_local);

	else

		schedstat_inc(p, se.nr_wakeups_remote);

	update_rq_clock(rq);

	activate_task(rq, p, 1);

	/*
@@ -2118,22 +2158,6 @@ static void pull_task(struct rq *src_rq, struct task_struct *p, 
	check_preempt_curr(this_rq, p);

}



/*

 * Is this task likely cache-hot:

 */

static inline int

task_hot(struct task_struct *p, u64 now, struct sched_domain *sd)

{

	s64 delta;



	if (p->sched_class != &fair_sched_class)

		return 0;



	delta = now - p->se.exec_start;



	return delta < (s64)sysctl_sched_migration_cost;

}



/*

 * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?

 */
@@ -2148,12 +2172,16 @@ int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu, 
	 * 2) cannot be migrated to this CPU due to cpus_allowed, or

	 * 3) are cache-hot on their current CPU.

	 */

	if (!cpu_isset(this_cpu, p->cpus_allowed))

	if (!cpu_isset(this_cpu, p->cpus_allowed)) {

		schedstat_inc(p, se.nr_failed_migrations_affine);

		return 0;

	}

	*all_pinned = 0;



	if (task_running(rq, p))

	if (task_running(rq, p)) {

		schedstat_inc(p, se.nr_failed_migrations_running);

		return 0;

	}



	/*

	 * Aggressive migration if:
@@ -2163,14 +2191,18 @@ int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu, 


	if (sd->nr_balance_failed > sd->cache_nice_tries) {

#ifdef CONFIG_SCHEDSTATS

		if (task_hot(p, rq->clock, sd))

		if (task_hot(p, rq->clock, sd)) {

			schedstat_inc(sd, lb_hot_gained[idle]);

			schedstat_inc(p, se.nr_forced_migrations);

		}

#endif

		return 1;

	}



	if (task_hot(p, rq->clock, sd))

	if (task_hot(p, rq->clock, sd)) {

		schedstat_inc(p, se.nr_failed_migrations_hot);

		return 0;

	}

	return 1;

}

kernel/sched_debug.c

+77 −10
Original line number Diff line number Diff line
@@ -260,6 +260,7 @@ __initcall(init_sched_debug_procfs); 


void proc_sched_show_task(struct task_struct *p, struct seq_file *m)

{

	unsigned long nr_switches;

	unsigned long flags;

	int num_threads = 1;
@@ -273,8 +274,12 @@ void proc_sched_show_task(struct task_struct *p, struct seq_file *m) 
	SEQ_printf(m, "%s (%d, #threads: %d)\n", p->comm, p->pid, num_threads);

	SEQ_printf(m,

		"---------------------------------------------------------\n");

#define __P(F) \

	SEQ_printf(m, "%-35s:%21Ld\n", #F, (long long)F)

#define P(F) \

	SEQ_printf(m, "%-35s:%21Ld\n", #F, (long long)p->F)

#define __PN(F) \

	SEQ_printf(m, "%-35s:%14Ld.%06ld\n", #F, SPLIT_NS((long long)F))

#define PN(F) \

	SEQ_printf(m, "%-35s:%14Ld.%06ld\n", #F, SPLIT_NS((long long)p->F))
@@ -282,6 +287,8 @@ void proc_sched_show_task(struct task_struct *p, struct seq_file *m) 
	PN(se.vruntime);

	PN(se.sum_exec_runtime);



	nr_switches = p->nvcsw + p->nivcsw;



#ifdef CONFIG_SCHEDSTATS

	PN(se.wait_start);

	PN(se.sleep_start);
@@ -292,14 +299,55 @@ void proc_sched_show_task(struct task_struct *p, struct seq_file *m) 
	PN(se.slice_max);

	PN(se.wait_max);

	P(sched_info.bkl_count);

	P(se.nr_migrations);

	P(se.nr_migrations_cold);

	P(se.nr_failed_migrations_affine);

	P(se.nr_failed_migrations_running);

	P(se.nr_failed_migrations_hot);

	P(se.nr_forced_migrations);

	P(se.nr_forced2_migrations);

	P(se.nr_wakeups);

	P(se.nr_wakeups_sync);

	P(se.nr_wakeups_migrate);

	P(se.nr_wakeups_local);

	P(se.nr_wakeups_remote);

	P(se.nr_wakeups_affine);

	P(se.nr_wakeups_affine_attempts);

	P(se.nr_wakeups_passive);

	P(se.nr_wakeups_idle);



	{

		u64 avg_atom, avg_per_cpu;



		avg_atom = p->se.sum_exec_runtime;

		if (nr_switches)

			do_div(avg_atom, nr_switches);

		else

			avg_atom = -1LL;



		avg_per_cpu = p->se.sum_exec_runtime;

		if (p->se.nr_migrations)

			avg_per_cpu = div64_64(avg_per_cpu, p->se.nr_migrations);

		else

			avg_per_cpu = -1LL;



		__PN(avg_atom);

		__PN(avg_per_cpu);

	}

#endif

	__P(nr_switches);

	SEQ_printf(m, "%-35s:%21Ld\n",

		   "nr_voluntary_switches", (long long)p->nvcsw);

	SEQ_printf(m, "%-35s:%21Ld\n",

		   "nr_switches", (long long)(p->nvcsw + p->nivcsw));

		   "nr_involuntary_switches", (long long)p->nivcsw);



	P(se.load.weight);

	P(policy);

	P(prio);

#undef P

#undef PN

#undef __PN

#undef P

#undef __P



	{

		u64 t0, t1;
@@ -314,13 +362,32 @@ void proc_sched_show_task(struct task_struct *p, struct seq_file *m) 
void proc_sched_set_task(struct task_struct *p)

{

#ifdef CONFIG_SCHEDSTATS

	p->se.wait_max				= 0;

	p->se.sleep_max				= 0;

	p->se.sum_sleep_runtime			= 0;

	p->se.block_max				= 0;

	p->se.exec_max				= 0;

	p->se.slice_max				= 0;

	p->se.wait_max			= 0;

	p->se.nr_migrations			= 0;

	p->se.nr_migrations_cold		= 0;

	p->se.nr_failed_migrations_affine	= 0;

	p->se.nr_failed_migrations_running	= 0;

	p->se.nr_failed_migrations_hot		= 0;

	p->se.nr_forced_migrations		= 0;

	p->se.nr_forced2_migrations		= 0;

	p->se.nr_wakeups			= 0;

	p->se.nr_wakeups_sync			= 0;

	p->se.nr_wakeups_migrate		= 0;

	p->se.nr_wakeups_local			= 0;

	p->se.nr_wakeups_remote			= 0;

	p->se.nr_wakeups_affine			= 0;

	p->se.nr_wakeups_affine_attempts	= 0;

	p->se.nr_wakeups_passive		= 0;

	p->se.nr_wakeups_idle			= 0;

	p->sched_info.bkl_count			= 0;

#endif

	p->se.sum_exec_runtime			= 0;

	p->se.prev_sum_exec_runtime		= 0;

	p->nvcsw				= 0;

	p->nivcsw				= 0;

}