From: paulmck@kernel.org
To: rcu@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com,
mingo@kernel.org, jiangshanlai@gmail.com,
akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org,
rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com,
fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org,
"Paul E. McKenney" <paulmck@kernel.org>
Subject: [PATCH tip/core/rcu 08/17] rcutorture: Use torture_hrtimeout_jiffies() to avoid busy-waits
Date: Wed, 6 Jan 2021 09:17:01 -0800 [thread overview]
Message-ID: <20210106171710.22239-8-paulmck@kernel.org> (raw)
In-Reply-To: <20210106171532.GA20769@paulmck-ThinkPad-P72>
From: "Paul E. McKenney" <paulmck@kernel.org>
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>
---
kernel/rcu/rcutorture.c | 26 +++++++-------------------
1 file changed, 7 insertions(+), 19 deletions(-)
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 1b70aa4..7b61086 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -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:
--
2.9.5
next prev parent reply other threads:[~2021-01-06 17:19 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-06 17:15 [PATCH tip/core/rcu 0/17] Torture-test updates for v5.12 Paul E. McKenney
2021-01-06 17:16 ` [PATCH tip/core/rcu 01/17] rcutorture: Add testing for RCU's global memory ordering paulmck
2021-01-06 17:16 ` [PATCH tip/core/rcu 02/17] scftorture: Add debug output for wrong-CPU warning paulmck
2021-01-06 17:16 ` [PATCH tip/core/rcu 03/17] refscale: Allow summarization of verbose output paulmck
2021-01-06 17:16 ` [PATCH tip/core/rcu 04/17] rcutorture: Require entire stutter period be post-boot paulmck
2021-01-06 17:16 ` [PATCH tip/core/rcu 05/17] rcutorture: Make synctype[] and nsynctype be static global paulmck
2021-01-06 17:16 ` [PATCH tip/core/rcu 06/17] rcutorture: Make rcu_torture_fakewriter() use blocking wait primitives paulmck
2021-01-06 17:17 ` [PATCH tip/core/rcu 07/17] torture: Add fuzzed hrtimer-based sleep functions paulmck
2021-01-06 17:17 ` paulmck [this message]
2021-01-06 17:17 ` [PATCH tip/core/rcu 09/17] torture: Make stutter use torture_hrtimeout_*() functions paulmck
2021-01-06 17:17 ` [PATCH tip/core/rcu 10/17] rcutorture: Use hrtimers for reader and writer delays paulmck
2021-01-06 17:17 ` [PATCH tip/core/rcu 11/17] torture: Make refscale throttle high-rate printk()s paulmck
2021-01-06 17:17 ` [PATCH tip/core/rcu 12/17] torture: Throttle VERBOSE_TOROUT_*() output paulmck
2021-01-06 17:17 ` [PATCH tip/core/rcu 13/17] rcutorture: Make object_debug also double call_rcu() heap object paulmck
2021-01-06 17:17 ` [PATCH tip/core/rcu 14/17] torture: Clean up after torture-test CPU hotplugging paulmck
2021-01-06 17:17 ` [PATCH tip/core/rcu 15/17] torture: Maintain torture-specific set of CPUs-online books paulmck
2021-01-06 17:17 ` [PATCH tip/core/rcu 16/17] torture: Break affinity of kthreads last running on outgoing CPU paulmck
2021-01-06 17:17 ` [PATCH tip/core/rcu 17/17] rcutorture: Add rcutree.use_softirq=0 to RUDE01 and TASKS01 paulmck
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