Commit-ID: 3025520ec424df8b0fd5cdc319ad6b83406d9954
Gitweb: https://git.kernel.org/tip/3025520ec424df8b0fd5cdc319ad6b83406d9954
Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
AuthorDate: Tue, 22 May 2018 11:38:47 -0700
Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
CommitDate: Thu, 12 Jul 2018 15:42:04 -0700
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@xxxxxxxxxxxxxxxxxx>
[ paulmck: Make rcu_torture_timer_rand static, per 0day Test Robot report. ]
---
include/linux/torture.h | 2 ++
kernel/rcu/rcutorture.c | 10 +++++-----
2 files changed, 7 insertions(+), 5 deletions(-)
diff --git a/include/linux/torture.h b/include/linux/torture.h
index a55e80817dae..61dfd93b6ee4 100644
--- a/include/linux/torture.h
+++ b/include/linux/torture.h
@@ -64,6 +64,8 @@ struct torture_random_state {
long trs_count;
};
#define DEFINE_TORTURE_RANDOM(name) struct torture_random_state name = { 0, 0 }
+#define DEFINE_TORTURE_RANDOM_PERCPU(name) \
+ DEFINE_PER_CPU(struct torture_random_state, name)
unsigned long torture_random(struct torture_random_state *trsp);
/* Task shuffler, which causes CPUs to occasionally go idle. */
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 2452e4a29923..d5a5465d2507 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) {
--
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