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: Ingo Molnar <mingo@elte.hu> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
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@ -250,6 +250,9 @@ struct cfs_rq {
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* It is set to NULL otherwise (i.e when none are currently running).
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*/
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struct sched_entity *curr;
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unsigned long nr_spread_over;
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#ifdef CONFIG_FAIR_GROUP_SCHED
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struct rq *rq; /* cpu runqueue to which this cfs_rq is attached */
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@ -140,6 +140,8 @@ void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq)
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SEQ_printf(m, " .%-30s: %ld\n", "bkl_cnt",
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rq->bkl_cnt);
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#endif
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SEQ_printf(m, " .%-30s: %ld\n", "nr_spread_over",
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cfs_rq->nr_spread_over);
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}
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static void print_cpu(struct seq_file *m, int cpu)
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@ -447,6 +447,19 @@ static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
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#endif
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}
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static void check_spread(struct cfs_rq *cfs_rq, struct sched_entity *se)
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{
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#ifdef CONFIG_SCHED_DEBUG
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s64 d = se->vruntime - cfs_rq->min_vruntime;
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if (d < 0)
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d = -d;
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if (d > 3*sysctl_sched_latency)
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schedstat_inc(cfs_rq, nr_spread_over);
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#endif
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}
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static void
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place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
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{
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@ -494,6 +507,7 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int wakeup)
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}
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update_stats_enqueue(cfs_rq, se);
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check_spread(cfs_rq, se);
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if (se != cfs_rq->curr)
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__enqueue_entity(cfs_rq, se);
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account_entity_enqueue(cfs_rq, se);
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@ -587,6 +601,7 @@ static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev)
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update_stats_curr_end(cfs_rq, prev);
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check_spread(cfs_rq, prev);
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if (prev->on_rq) {
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update_stats_wait_start(cfs_rq, prev);
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/* Put 'current' back into the tree. */
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@ -996,6 +1011,8 @@ static void task_new_fair(struct rq *rq, struct task_struct *p)
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}
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update_stats_enqueue(cfs_rq, se);
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check_spread(cfs_rq, se);
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check_spread(cfs_rq, curr);
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__enqueue_entity(cfs_rq, se);
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account_entity_enqueue(cfs_rq, se);
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resched_task(rq->curr);
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