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rcutorture: Use per-CPU random state for rcu_torture_timer()

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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. ]
This commit is contained in:
Paul E. McKenney 2018-05-22 11:38:47 -07:00
parent 8da9a59523
commit 3025520ec4
2 changed files with 7 additions and 5 deletions
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2
include/linux/torture.h
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@ -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. */

10
kernel/rcu/rcutorture.c
View file

@ -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) {