Commit 69a79bb1 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcu: Track rcu_nocb_kthread()'s sleeping and awakening 



This commit adds event traces to track all of rcu_nocb_kthread()'s
blocking and awakening.

Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent 756cbf6b

include/trace/events/rcu.h

+4 −0
Original line number Diff line number Diff line
@@ -183,8 +183,12 @@ TRACE_EVENT(rcu_grace_period_init, 
 *	"WakeOvf": Wake rcuo kthread, CB list is huge.

 *	"WakeNot": Don't wake rcuo kthread.

 *	"WakeNotPoll": Don't wake rcuo kthread because it is polling.

 *	"Poll": Start of new polling cycle for rcu_nocb_poll.

 *	"Sleep": Sleep waiting for CBs for !rcu_nocb_poll.

 *	"WokeEmpty": rcuo kthread woke to find empty list.

 *	"WokeNonEmpty": rcuo kthread woke to find non-empty list.

 *	"WaitQueue": Enqueue partially done, timed wait for it to complete.

 *	"WokeQueue": Partial enqueue now complete.

 */

TRACE_EVENT(rcu_nocb_wake,

kernel/rcutree_plugin.h

+14 −1
Original line number Diff line number Diff line
@@ -2230,6 +2230,7 @@ static void rcu_nocb_wait_gp(struct rcu_data *rdp) 
static int rcu_nocb_kthread(void *arg)

{

	int c, cl;

	bool firsttime = 1;

	struct rcu_head *list;

	struct rcu_head *next;

	struct rcu_head **tail;
@@ -2238,8 +2239,15 @@ static int rcu_nocb_kthread(void *arg) 
	/* Each pass through this loop invokes one batch of callbacks */

	for (;;) {

		/* If not polling, wait for next batch of callbacks. */

		if (!rcu_nocb_poll)

		if (!rcu_nocb_poll) {

			trace_rcu_nocb_wake(rdp->rsp->name, rdp->cpu,

					    TPS("Sleep"));

			wait_event_interruptible(rdp->nocb_wq, rdp->nocb_head);

		} else if (firsttime) {

			firsttime = 0;

			trace_rcu_nocb_wake(rdp->rsp->name, rdp->cpu,

					    TPS("Poll"));

		}

		list = ACCESS_ONCE(rdp->nocb_head);

		if (!list) {

			if (!rcu_nocb_poll)
@@ -2249,6 +2257,7 @@ static int rcu_nocb_kthread(void *arg) 
			flush_signals(current);

			continue;

		}

		firsttime = 1;

		trace_rcu_nocb_wake(rdp->rsp->name, rdp->cpu,

				    TPS("WokeNonEmpty"));
@@ -2271,7 +2280,11 @@ static int rcu_nocb_kthread(void *arg) 
			next = list->next;

			/* Wait for enqueuing to complete, if needed. */

			while (next == NULL && &list->next != tail) {

				trace_rcu_nocb_wake(rdp->rsp->name, rdp->cpu,

						    TPS("WaitQueue"));

				schedule_timeout_interruptible(1);

				trace_rcu_nocb_wake(rdp->rsp->name, rdp->cpu,

						    TPS("WokeQueue"));

				next = list->next;

			}

			debug_rcu_head_unqueue(list);