rcu/nocb: Rename and document no-CB CB kthread sleep trace event

The nocb_cb_wait() function traces a "FollowerSleep" trace_rcu_nocb_wake()
event, which never was documented and is now misleading.  This commit
therefore changes "FollowerSleep" to "CBSleep", documents this, and
updates the documentation for "Sleep" as well.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>

diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h
index 02a3f78..313324d 100644 (file)
--- a/include/trace/events/rcu.h
+++ b/include/trace/events/rcu.h
@@ -267,7 +267,8 @@ TRACE_EVENT_RCU(rcu_exp_funnel_lock,
  *     "WakeNotPoll": Don't wake rcuo kthread because it is polling.
  *     "DeferredWake": Carried out the "IsDeferred" wakeup.
  *     "Poll": Start of new polling cycle for rcu_nocb_poll.
- *     "Sleep": Sleep waiting for CBs for !rcu_nocb_poll.
+ *     "Sleep": Sleep waiting for GP for !rcu_nocb_poll.
+ *     "CBSleep": 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.

diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 0af36e9..be065aa 100644 (file)
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -1891,7 +1891,7 @@ static int rcu_nocb_gp_kthread(void *arg)
  */
 static bool nocb_cb_wait(struct rcu_data *rdp)
 {
-       trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("FollowerSleep"));
+       trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("CBSleep"));
        swait_event_interruptible_exclusive(rdp->nocb_cb_wq,
                                 READ_ONCE(rdp->nocb_cb_head));
        if (smp_load_acquire(&rdp->nocb_cb_head)) { /* VVV */