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Commit 2cf27b65 authored by Matt Wagantall's avatar Matt Wagantall
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sched/rt: print RT tasks when RT throttling is activated 



Existing debug prints do not provide any clues about which tasks
may have triggered RT throttling. Print the names and PIDs of
all tasks on the throttled rt_rq to help narrow down the source
of the problem.

Change-Id: I180534c8a647254ed38e89d0c981a8f8bccd741c
Signed-off-by: default avatarMatt Wagantall <mattw@codeaurora.org>
parent 82f65cf9

kernel/sched/rt.c

+37 −1
Original line number Diff line number Diff line
@@ -823,6 +823,42 @@ static inline int rt_se_prio(struct sched_rt_entity *rt_se) 
	return rt_task_of(rt_se)->prio;

}



static void dump_throttled_rt_tasks(struct rt_rq *rt_rq)

{

	struct rt_prio_array *array = &rt_rq->active;

	struct sched_rt_entity *rt_se;

	char buf[500];

	char *pos = buf;

	char *end = buf + sizeof(buf);

	int idx;



	pos += snprintf(pos, sizeof(buf),

		"sched: RT throttling activated for rt_rq %p (cpu %d)\n",

		rt_rq, cpu_of(rq_of_rt_rq(rt_rq)));



	if (bitmap_empty(array->bitmap, MAX_RT_PRIO))

		goto out;



	pos += snprintf(pos, end - pos, "potential CPU hogs:\n");

	idx = sched_find_first_bit(array->bitmap);

	while (idx < MAX_RT_PRIO) {

		list_for_each_entry(rt_se, array->queue + idx, run_list) {

			struct task_struct *p;



			if (!rt_entity_is_task(rt_se))

				continue;



			p = rt_task_of(rt_se);

			if (pos < end)

				pos += snprintf(pos, end - pos, "\t%s (%d)\n",

					p->comm, p->pid);

		}

		idx = find_next_bit(array->bitmap, MAX_RT_PRIO, idx + 1);

	}

out:

	printk_sched("%s", buf);

}



static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)

{

	u64 runtime = sched_rt_runtime(rt_rq);
@@ -852,7 +888,7 @@ static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq) 


			if (!once) {

				once = true;

				printk_sched("sched: RT throttling activated\n");

				dump_throttled_rt_tasks(rt_rq);

			}

		} else {

			/*