refperf: Simplify initialization-time wakeup protocol

This commit moves the reader-launch wait loop from ref_perf_init()
to main_func(), removing one layer of wakeup and allowing slightly
faster system boot.

Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

diff --git a/kernel/rcu/refperf.c b/kernel/rcu/refperf.c
index 2d2d227d761aa9cd794f58d611cf761a2ab87093..7839237ffc177f5691f835436790ae0aee41f46e 100644 (file)
--- a/kernel/rcu/refperf.c
+++ b/kernel/rcu/refperf.c
@@ -369,13 +369,14 @@ static int main_func(void *arg)
                VERBOSE_PERFOUT_ERRSTRING("out of memory");
                errexit = true;
        }
-       atomic_inc(&n_init);
-
-       // Wait for all threads to start.
-       wait_event(main_wq, atomic_read(&n_init) == (nreaders + 1));
        if (holdoff)
                schedule_timeout_interruptible(holdoff * HZ);
 
+       // Wait for all threads to start.
+       atomic_inc(&n_init);
+       while (atomic_read(&n_init) < nreaders + 1)
+               schedule_timeout_uninterruptible(1);
+
        // Start exp readers up per experiment
        for (exp = 0; exp < nruns && !torture_must_stop(); exp++) {
                if (errexit)
@@ -565,14 +566,6 @@ ref_perf_init(void)
        firsterr = torture_create_kthread(main_func, NULL, main_task);
        if (firsterr)
                goto unwind;
-       schedule_timeout_uninterruptible(1);
-
-
-       // Wait until all threads start
-       while (atomic_read(&n_init) < nreaders + 1)
-               schedule_timeout_uninterruptible(1);
-
-       wake_up(&main_wq);
 
        torture_init_end();
        return 0;