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Commit ddc97297 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
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sched debug: check spread 



debug feature: check how well we schedule within a reasonable
vruntime 'spread' range. (note that CPU overload can increase
the spread, so this is not a hard condition, but normal loads
should be within the spread.)

Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
parent d822cece

kernel/sched.c

+3 −0
Original line number Diff line number Diff line
@@ -250,6 +250,9 @@ struct cfs_rq { 
	 * It is set to NULL otherwise (i.e when none are currently running).

	 */

	struct sched_entity *curr;



	unsigned long nr_spread_over;



#ifdef CONFIG_FAIR_GROUP_SCHED

	struct rq *rq;	/* cpu runqueue to which this cfs_rq is attached */

kernel/sched_debug.c

+2 −0
Original line number Diff line number Diff line
@@ -140,6 +140,8 @@ void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq) 
	SEQ_printf(m, "  .%-30s: %ld\n", "bkl_cnt",

			rq->bkl_cnt);

#endif

	SEQ_printf(m, "  .%-30s: %ld\n", "nr_spread_over",

			cfs_rq->nr_spread_over);

}



static void print_cpu(struct seq_file *m, int cpu)

kernel/sched_fair.c

+17 −0
Original line number Diff line number Diff line
@@ -447,6 +447,19 @@ static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se) 
#endif

}



static void check_spread(struct cfs_rq *cfs_rq, struct sched_entity *se)

{

#ifdef CONFIG_SCHED_DEBUG

	s64 d = se->vruntime - cfs_rq->min_vruntime;



	if (d < 0)

		d = -d;



	if (d > 3*sysctl_sched_latency)

		schedstat_inc(cfs_rq, nr_spread_over);

#endif

}



static void

place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)

{
@@ -494,6 +507,7 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int wakeup) 
	}



	update_stats_enqueue(cfs_rq, se);

	check_spread(cfs_rq, se);

	if (se != cfs_rq->curr)

		__enqueue_entity(cfs_rq, se);

	account_entity_enqueue(cfs_rq, se);
@@ -587,6 +601,7 @@ static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev) 


	update_stats_curr_end(cfs_rq, prev);



	check_spread(cfs_rq, prev);

	if (prev->on_rq) {

		update_stats_wait_start(cfs_rq, prev);

		/* Put 'current' back into the tree. */
@@ -996,6 +1011,8 @@ static void task_new_fair(struct rq *rq, struct task_struct *p) 
	}



	update_stats_enqueue(cfs_rq, se);

	check_spread(cfs_rq, se);

	check_spread(cfs_rq, curr);

	__enqueue_entity(cfs_rq, se);

	account_entity_enqueue(cfs_rq, se);

	resched_task(rq->curr);