linux-kernel - [PATCH tip/core/rcu 06/24] rcutorture: Bind rcuperf reader/writer kthreads to CPUs

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Date:	Tue, 12 Apr 2016 08:43:39 -0700
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	linux-kernel@...r.kernel.org
Cc:	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,
	dvhart@...ux.intel.com, fweisbec@...il.com, oleg@...hat.com,
	bobby.prani@...il.com,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 06/24] rcutorture: Bind rcuperf reader/writer kthreads to CPUs

This commit forces more deterministic behavior by binding rcuperf's
rcu_perf_reader() and rcu_perf_writer() kthreads to their respective
CPUs.

Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
---
 kernel/rcu/rcuperf.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/kernel/rcu/rcuperf.c b/kernel/rcu/rcuperf.c
index 9d54a57bee7d..7a1edf417d18 100644
--- a/kernel/rcu/rcuperf.c
+++ b/kernel/rcu/rcuperf.c
@@ -328,8 +328,10 @@ rcu_perf_reader(void *arg)
 {
 	unsigned long flags;
 	int idx;
+	long me = (long)arg;
 
 	VERBOSE_PERFOUT_STRING("rcu_perf_reader task started");
+	set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
 	set_user_nice(current, MAX_NICE);
 	atomic_inc(&n_rcu_perf_reader_started);
 
@@ -362,6 +364,7 @@ rcu_perf_writer(void *arg)
 	WARN_ON(rcu_gp_is_expedited() && !rcu_gp_is_normal() && !gp_exp);
 	WARN_ON(rcu_gp_is_normal() && gp_exp);
 	WARN_ON(!wdpp);
+	set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
 	t = ktime_get_mono_fast_ns();
 	if (atomic_inc_return(&n_rcu_perf_writer_started) >= nrealwriters) {
 		t_rcu_perf_writer_started = t;
@@ -594,7 +597,7 @@ rcu_perf_init(void)
 		goto unwind;
 	}
 	for (i = 0; i < nrealreaders; i++) {
-		firsterr = torture_create_kthread(rcu_perf_reader, NULL,
+		firsterr = torture_create_kthread(rcu_perf_reader, (void *)i,
 						  reader_tasks[i]);
 		if (firsterr)
 			goto unwind;
-- 
2.5.2