From: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Date: Tue, 22 May 2018 18:38:47 +0000 (-0700) Subject: rcutorture: Use per-CPU random state for rcu_torture_timer() X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=3025520ec424df8b0fd5cdc319ad6b83406d9954;p=openwrt%2Fstaging%2Fblogic.git 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/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) {