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rcu: Track rcu_nocb_kthread()'s sleeping and awakening

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

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney 2013-08-15 13:23:23 -07:00
parent 756cbf6bef
commit 69a79bb12a
2 changed files with 18 additions and 1 deletions
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4
include/trace/events/rcu.h
View file

@ -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,

15
kernel/rcutree_plugin.h
View file

@ -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);