rcutorture: Use hrtimers for reader and writer delays

This commit replaces schedule_timeout_uninterruptible() and
schedule_timeout_interruptible() with torture_hrtimeout_us() and
torture_hrtimeout_jiffies() to avoid timer-wheel synchronization.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

kernel/rcu/rcutorture.c

@@ -1149,7 +1149,7 @@ rcu_torture_writer(void *arg)
 
 	do {
 		rcu_torture_writer_state = RTWS_FIXED_DELAY;
-		schedule_timeout_uninterruptible(1);
+		torture_hrtimeout_us(500, 1000, &rand);
 		rp = rcu_torture_alloc();
 		if (rp == NULL)
 			continue;
@@ -1290,8 +1290,7 @@ rcu_torture_fakewriter(void *arg)
 	set_user_nice(current, MAX_NICE);
 
 	do {
-		schedule_timeout_uninterruptible(1 + torture_random(&rand)%10);
-		udelay(torture_random(&rand) & 0x3ff);
+		torture_hrtimeout_jiffies(torture_random(&rand) % 10, &rand);
 		if (cur_ops->cb_barrier != NULL &&
 		    torture_random(&rand) % (nfakewriters * 8) == 0) {
 			cur_ops->cb_barrier();
@@ -1656,7 +1655,7 @@ rcu_torture_reader(void *arg)
 		if (!rcu_torture_one_read(&rand, myid) && !torture_must_stop())
 			schedule_timeout_interruptible(HZ);
 		if (time_after(jiffies, lastsleep) && !torture_must_stop()) {
-			schedule_timeout_interruptible(1);
+			torture_hrtimeout_us(500, 1000, &rand);
 			lastsleep = jiffies + 10;
 		}
 		while (num_online_cpus() < mynumonline && !torture_must_stop())