Commit-ID: 5ab7ab8362fa8a4f7995d65ea05edf71530e8004
Gitweb: https://git.kernel.org/tip/5ab7ab8362fa8a4f7995d65ea05edf71530e8004
Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxx>
AuthorDate: Fri, 21 Sep 2018 18:08:09 -0700
Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxx>
CommitDate: Sat, 1 Dec 2018 12:45:34 -0800
rcutorture: Affinity forward-progress test to avoid housekeeping CPUs
This commit affinities the forward-progress tests to avoid hogging a
housekeeping CPU on the theory that the offloaded callbacks will be
running on those housekeeping CPUs.
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxx>
[ paulmck: Fix NULL-pointer issue located by kbuild test robot. ]
Tested-by: Rong Chen <rong.a.chen@xxxxxxxxx>
---
kernel/rcu/rcu.h | 2 ++
kernel/rcu/rcutorture.c | 1 +
kernel/rcu/tree_plugin.h | 11 +++++++++++
3 files changed, 14 insertions(+)
diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h
index 2866166863f0..0f0f5ae8c3d4 100644
--- a/kernel/rcu/rcu.h
+++ b/kernel/rcu/rcu.h
@@ -539,8 +539,10 @@ extern struct workqueue_struct *rcu_par_gp_wq;
#ifdef CONFIG_RCU_NOCB_CPU
bool rcu_is_nocb_cpu(int cpu);
+void rcu_bind_current_to_nocb(void);
#else
static inline bool rcu_is_nocb_cpu(int cpu) { return false; }
+static inline void rcu_bind_current_to_nocb(void) { }
#endif
#endif /* __LINUX_RCU_H */
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index bcc33bb8d9a6..36a3bc42782d 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -1803,6 +1803,7 @@ static int rcu_torture_fwd_prog(void *args)
int tested_tries = 0;
VERBOSE_TOROUT_STRING("rcu_torture_fwd_progress task started");
+ rcu_bind_current_to_nocb();
if (!IS_ENABLED(CONFIG_SMP) || !IS_ENABLED(CONFIG_RCU_BOOST))
set_user_nice(current, MAX_NICE);
do {
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 605ff3b06098..25fe26c4e9c1 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -2603,6 +2603,17 @@ static bool init_nocb_callback_list(struct rcu_data *rdp)
return true;
}
+/*
+ * Bind the current task to the offloaded CPUs. If there are no offloaded
+ * CPUs, leave the task unbound. Splat if the bind attempt fails.
+ */
+void rcu_bind_current_to_nocb(void)
+{
+ if (cpumask_available(rcu_nocb_mask) && cpumask_weight(rcu_nocb_mask))
+ WARN_ON(sched_setaffinity(current->pid, rcu_nocb_mask));
+}
+EXPORT_SYMBOL_GPL(rcu_bind_current_to_nocb);
+
#else /* #ifdef CONFIG_RCU_NOCB_CPU */
static bool rcu_nocb_cpu_needs_barrier(int cpu)
|