linux-kernel - [PATCH tip/core/rcu 07/24] rcutorture: Set rcuperf writer kthreads to real-time priority

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Message-Id: <1460475837-26498-7-git-send-email-paulmck@linux.vnet.ibm.com>
Date:	Tue, 12 Apr 2016 08:43:40 -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 07/24] rcutorture: Set rcuperf writer kthreads to real-time priority

This commit forces more deterministic update-side behavior by setting
rcuperf's rcu_perf_writer() kthreads to real-time priority.

Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
---
 kernel/rcu/rcuperf.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/rcu/rcuperf.c b/kernel/rcu/rcuperf.c
index 7a1edf417d18..e18d016a9888 100644
--- a/kernel/rcu/rcuperf.c
+++ b/kernel/rcu/rcuperf.c
@@ -355,6 +355,7 @@ rcu_perf_writer(void *arg)
 	int i = 0;
 	int i_max;
 	long me = (long)arg;
+	struct sched_param sp;
 	bool started = false, done = false, alldone = false;
 	u64 t;
 	u64 *wdp;
@@ -365,6 +366,8 @@ rcu_perf_writer(void *arg)
 	WARN_ON(rcu_gp_is_normal() && gp_exp);
 	WARN_ON(!wdpp);
 	set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
+	sp.sched_priority = 1;
+	sched_setscheduler_nocheck(current, SCHED_FIFO, &sp);
 	t = ktime_get_mono_fast_ns();
 	if (atomic_inc_return(&n_rcu_perf_writer_started) >= nrealwriters) {
 		t_rcu_perf_writer_started = t;
-- 
2.5.2