[tip: core/rcu] refperf: Simplify initialization-time wakeup protocol
From: tip-bot2 for Paul E. McKenney
Date: Fri Jul 31 2020 - 05:26:16 EST
The following commit has been merged into the core/rcu branch of tip:
Commit-ID: 96af8669591d740a1e2695c4d96e544409dbf896
Gitweb: https://git.kernel.org/tip/96af8669591d740a1e2695c4d96e544409dbf896
Author: Paul E. McKenney <paulmck@xxxxxxxxxx>
AuthorDate: Wed, 27 May 2020 16:46:56 -07:00
Committer: Paul E. McKenney <paulmck@xxxxxxxxxx>
CommitterDate: Mon, 29 Jun 2020 12:00:45 -07:00
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@xxxxxxxxxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
---
kernel/rcu/refperf.c | 17 +++++------------
1 file changed, 5 insertions(+), 12 deletions(-)
diff --git a/kernel/rcu/refperf.c b/kernel/rcu/refperf.c
index 2d2d227..7839237 100644
--- 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;