linux-kernel - [PATCH tip/core/rcu 04/12] rcu: Fix tracepoint tracking RCU CPU kthread utilization

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Message-Id: <20191210040741.2943-4-paulmck@kernel.org>
Date:   Mon,  9 Dec 2019 20:07:33 -0800
From:   paulmck@...nel.org
To:     rcu@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, kernel-team@...com, mingo@...nel.org,
        jiangshanlai@...il.com, dipankar@...ibm.com,
        akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
        josh@...htriplett.org, tglx@...utronix.de, peterz@...radead.org,
        rostedt@...dmis.org, dhowells@...hat.com, edumazet@...gle.com,
        fweisbec@...il.com, oleg@...hat.com, joel@...lfernandes.org,
        Lai Jiangshan <laijs@...ux.alibaba.com>,
        "Paul E . McKenney" <paulmck@...nel.org>
Subject: [PATCH tip/core/rcu 04/12] rcu: Fix tracepoint tracking RCU CPU kthread utilization

From: Lai Jiangshan <laijs@...ux.alibaba.com>

In the call to trace_rcu_utilization() at the start of the loop in
rcu_cpu_kthread(), "rcu_wait" is incorrect, plus this trace event needs
to be hoisted above the loop to balance with either the "rcu_wait" or
"rcu_yield", depending on how the loop exits.  This commit therefore
makes these changes.

Signed-off-by: Lai Jiangshan <jiangshanlai@...il.com>
Signed-off-by: Lai Jiangshan <laijs@...ux.alibaba.com>
Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
---
 kernel/rcu/tree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index dd8cfc3..ba154a3 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2474,8 +2474,8 @@ static void rcu_cpu_kthread(unsigned int cpu)
 	char work, *workp = this_cpu_ptr(&rcu_data.rcu_cpu_has_work);
 	int spincnt;
 
+	trace_rcu_utilization(TPS("Start CPU kthread@..._run"));
 	for (spincnt = 0; spincnt < 10; spincnt++) {
-		trace_rcu_utilization(TPS("Start CPU kthread@..._wait"));
 		local_bh_disable();
 		*statusp = RCU_KTHREAD_RUNNING;
 		local_irq_disable();
-- 
2.9.5