rcutorture: Use per-CPU random state for rcu_torture_timer()
Currently, the rcu_torture_timer() function uses a single global
torture_random_state structure protected by a single global lock.
This conflicts to some extent with performance and scalability,
but even more with the goal of consolidating read-side testing
with rcu_torture_reader(). This commit therefore creates a per-CPU
torture_random_state structure for use by rcu_torture_timer() and
eliminates the lock.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
[ paulmck: Make rcu_torture_timer_rand static, per 0day Test Robot report. ]
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 2452e4a..d5a5465 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -1143,6 +1143,8 @@ static bool rcu_torture_one_read(struct torture_random_state *trsp)
return true;
}
+static DEFINE_TORTURE_RANDOM_PERCPU(rcu_torture_timer_rand);
+
/*
* RCU torture reader from timer handler. Dereferences rcu_torture_current,
* incrementing the corresponding element of the pipeline array. The
@@ -1154,12 +1156,12 @@ static void rcu_torture_timer(struct timer_list *unused)
int idx;
unsigned long started;
unsigned long completed;
- static DEFINE_TORTURE_RANDOM(rand);
- static DEFINE_SPINLOCK(rand_lock);
struct rcu_torture *p;
int pipe_count;
+ struct torture_random_state *trsp;
unsigned long long ts;
+ trsp = this_cpu_ptr(&rcu_torture_timer_rand);
atomic_long_inc(&n_rcu_torture_timers);
idx = cur_ops->readlock();
started = cur_ops->get_gp_seq();
@@ -1176,9 +1178,7 @@ static void rcu_torture_timer(struct timer_list *unused)
}
if (p->rtort_mbtest == 0)
atomic_inc(&n_rcu_torture_mberror);
- spin_lock(&rand_lock);
- cur_ops->read_delay(&rand);
- spin_unlock(&rand_lock);
+ cur_ops->read_delay(trsp);
preempt_disable();
pipe_count = p->rtort_pipe_count;
if (pipe_count > RCU_TORTURE_PIPE_LEN) {
