rcu: Add event-trace markers to TREE_RCU kthreads

Add event-trace markers to TREE_RCU kthreads to allow including these
kthread's CPU time in the utilization calculations.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

2 files changed, 15 insertions, 0 deletions

diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h
index 508824e5a77d..ac52aba00a3e 100644
--- a/include/trace/events/rcu.h
+++ b/include/trace/events/rcu.h
@@ -13,6 +13,9 @@
  * "Start <activity>" -- Mark the start of the specified activity,
  *                       such as "context switch".  Nesting is permitted.
  * "End <activity>" -- Mark the end of the specified activity.
+ *
+ * An "@" character within "<activity>" is a comment character: Data
+ * reduction scripts will ignore the "@" and the remainder of the line.
  */
 TRACE_EVENT(rcu_utilization,
 
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index ecd48a2e3eeb..94d9ca1e4061 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -1219,9 +1219,12 @@ static int rcu_boost_kthread(void *arg)
         int spincnt = 0;
         int more2boost;
 
+        trace_rcu_utilization("Start boost kthread@init");
         for (;;) {
                 rnp->boost_kthread_status = RCU_KTHREAD_WAITING;
+                trace_rcu_utilization("End boost kthread@rcu_wait");
                 rcu_wait(rnp->boost_tasks || rnp->exp_tasks);
+                trace_rcu_utilization("Start boost kthread@rcu_wait");
                 rnp->boost_kthread_status = RCU_KTHREAD_RUNNING;
                 more2boost = rcu_boost(rnp);
                 if (more2boost)
@@ -1229,11 +1232,14 @@ static int rcu_boost_kthread(void *arg)
                 else
                         spincnt = 0;
                 if (spincnt > 10) {
+                        trace_rcu_utilization("End boost kthread@rcu_yield");
                         rcu_yield(rcu_boost_kthread_timer, (unsigned long)rnp);
+                        trace_rcu_utilization("Start boost kthread@rcu_yield");
                         spincnt = 0;
                 }
         }
         /* NOTREACHED */
+        trace_rcu_utilization("End boost kthread@notreached");
         return 0;
 }
 
@@ -1490,9 +1496,12 @@ static int rcu_cpu_kthread(void *arg)
         char work;
         char *workp = &per_cpu(rcu_cpu_has_work, cpu);
 
+        trace_rcu_utilization("Start CPU kthread@init");
         for (;;) {
                 *statusp = RCU_KTHREAD_WAITING;
+                trace_rcu_utilization("End CPU kthread@rcu_wait");
                 rcu_wait(*workp != 0 || kthread_should_stop());
+                trace_rcu_utilization("Start CPU kthread@rcu_wait");
                 local_bh_disable();
                 if (rcu_cpu_kthread_should_stop(cpu)) {
                         local_bh_enable();
@@ -1513,11 +1522,14 @@ static int rcu_cpu_kthread(void *arg)
                         spincnt = 0;
                 if (spincnt > 10) {
                         *statusp = RCU_KTHREAD_YIELDING;
+                        trace_rcu_utilization("End CPU kthread@rcu_yield");
                         rcu_yield(rcu_cpu_kthread_timer, (unsigned long)cpu);
+                        trace_rcu_utilization("Start CPU kthread@rcu_yield");
                         spincnt = 0;
                 }
         }
         *statusp = RCU_KTHREAD_STOPPED;
+        trace_rcu_utilization("End CPU kthread@term");
         return 0;
 }