linux-kernel - [PATCH tip/core/rcu 20/55] rcu: Add event-trace markers to TREE

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Date:	Tue,  6 Sep 2011 11:00:14 -0700
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	linux-kernel@...r.kernel.org
Cc:	mingo@...e.hu, laijs@...fujitsu.com, dipankar@...ibm.com,
	akpm@...ux-foundation.org, mathieu.desnoyers@...ymtl.ca,
	josh@...htriplett.org, niv@...ibm.com, tglx@...utronix.de,
	peterz@...radead.org, rostedt@...dmis.org, Valdis.Kletnieks@...edu,
	dhowells@...hat.com, eric.dumazet@...il.com, darren@...art.com,
	patches@...aro.org, "Paul E. McKenney" <paul.mckenney@...aro.org>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 20/55] rcu: Add event-trace markers to TREE_RCU kthreads

From: Paul E. McKenney <paul.mckenney@...aro.org>

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@...aro.org>
Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
---
 include/trace/events/rcu.h |    3 +++
 kernel/rcutree_plugin.h    |   12 ++++++++++++
 2 files changed, 15 insertions(+), 0 deletions(-)

diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h
index 508824e5..ac52aba 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 ecd48a2..94d9ca1 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@...t");
 	for (;;) {
 		rnp->boost_kthread_status = RCU_KTHREAD_WAITING;
+		trace_rcu_utilization("End boost kthread@..._wait");
 		rcu_wait(rnp->boost_tasks || rnp->exp_tasks);
+		trace_rcu_utilization("Start boost kthread@..._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@..._yield");
 			rcu_yield(rcu_boost_kthread_timer, (unsigned long)rnp);
+			trace_rcu_utilization("Start boost kthread@..._yield");
 			spincnt = 0;
 		}
 	}
 	/* NOTREACHED */
+	trace_rcu_utilization("End boost kthread@...reached");
 	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@...t");
 	for (;;) {
 		*statusp = RCU_KTHREAD_WAITING;
+		trace_rcu_utilization("End CPU kthread@..._wait");
 		rcu_wait(*workp != 0 || kthread_should_stop());
+		trace_rcu_utilization("Start CPU kthread@..._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@..._yield");
 			rcu_yield(rcu_cpu_kthread_timer, (unsigned long)cpu);
+			trace_rcu_utilization("Start CPU kthread@..._yield");
 			spincnt = 0;
 		}
 	}
 	*statusp = RCU_KTHREAD_STOPPED;
+	trace_rcu_utilization("End CPU kthread@...m");
 	return 0;
 }
 
-- 
1.7.3.2

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