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rcutorture: Use torture_hrtimeout_jiffies() to avoid busy-waits

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Because rcu_torture_writer() and rcu_torture_fakewriter() predate
hrtimers, they do timer-wheel-decoupled timed waits by using the
timer-wheel-based schedule_timeout_interruptible() functions in
conjunction with a random udelay()-based wait.  This latter unnecessarily
burns CPU time, so this commit instead uses torture_hrtimeout_jiffies()
to decouple from the timer wheels without busy-waiting.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit is contained in:
Paul E. McKenney 2020-11-17 11:32:54 -08:00
parent ae19aaafae
commit ea31fd9ca8
1 changed files with 7 additions and 19 deletions
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26
kernel/rcu/rcutorture.c
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@ -1194,10 +1194,7 @@ rcu_torture_writer(void *arg)
case RTWS_COND_GET:
rcu_torture_writer_state = RTWS_COND_GET;
gp_snap = cur_ops->get_gp_state();
i = torture_random(&rand) % 16;
if (i != 0)
schedule_timeout_interruptible(i);
udelay(torture_random(&rand) % 1000);
torture_hrtimeout_jiffies(torture_random(&rand) % 16, &rand);
rcu_torture_writer_state = RTWS_COND_SYNC;
cur_ops->cond_sync(gp_snap);
rcu_torture_pipe_update(old_rp);
@ -1206,12 +1203,9 @@ rcu_torture_writer(void *arg)
rcu_torture_writer_state = RTWS_POLL_GET;
gp_snap = cur_ops->start_gp_poll();
rcu_torture_writer_state = RTWS_POLL_WAIT;
while (!cur_ops->poll_gp_state(gp_snap)) {
i = torture_random(&rand) % 16;
if (i != 0)
schedule_timeout_interruptible(i);
udelay(torture_random(&rand) % 1000);
}
while (!cur_ops->poll_gp_state(gp_snap))
torture_hrtimeout_jiffies(torture_random(&rand) % 16,
&rand);
rcu_torture_pipe_update(old_rp);
break;
case RTWS_SYNC:
@ -1290,7 +1284,6 @@ static int
rcu_torture_fakewriter(void *arg)
{
unsigned long gp_snap;
int i;
DEFINE_TORTURE_RANDOM(rand);
VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task started");
@ -1311,19 +1304,14 @@ rcu_torture_fakewriter(void *arg)
break;
case RTWS_COND_GET:
gp_snap = cur_ops->get_gp_state();
i = torture_random(&rand) % 16;
if (i != 0)
schedule_timeout_interruptible(i);
udelay(torture_random(&rand) % 1000);
torture_hrtimeout_jiffies(torture_random(&rand) % 16, &rand);
cur_ops->cond_sync(gp_snap);
break;
case RTWS_POLL_GET:
gp_snap = cur_ops->start_gp_poll();
while (!cur_ops->poll_gp_state(gp_snap)) {
i = torture_random(&rand) % 16;
if (i != 0)
schedule_timeout_interruptible(i);
udelay(torture_random(&rand) % 1000);
torture_hrtimeout_jiffies(torture_random(&rand) % 16,
&rand);
}
break;
case RTWS_SYNC: