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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, dipankar@in.ibm.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 19/30] refperf: Simplify initialization-time wakeup protocol
Date: Mon, 22 Jun 2020 17:30:02 -0700	[thread overview]
Message-ID: <20200623003013.26252-19-paulmck@kernel.org> (raw)
In-Reply-To: <20200623002941.GA26089@paulmck-ThinkPad-P72>

From: "Paul E. McKenney" <paulmck@kernel.org>

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>
---
 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;
-- 
2.9.5


  parent reply	other threads:[~2020-06-23  0:31 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-23  0:29 [PATCH tip/core/rcu 0/30] Add read-side scalability tests for v5.9 Paul E. McKenney
2020-06-23  0:29 ` [PATCH tip/core/rcu 01/30] rcuperf: Remove useless while loops around wait_event paulmck
2020-06-23  0:29 ` [PATCH tip/core/rcu 02/30] refperf: Add a test to measure performance of read-side synchronization paulmck
2020-06-23  0:29 ` [PATCH tip/core/rcu 03/30] rcuperf: Add comments explaining the high reader overhead paulmck
2020-06-23  0:29 ` [PATCH tip/core/rcu 04/30] torture: Add refperf to the rcutorture scripting paulmck
2020-06-23  0:29 ` [PATCH tip/core/rcu 05/30] refperf: Add holdoff parameter to allow CPUs to come online paulmck
2020-06-23  0:29 ` [PATCH tip/core/rcu 06/30] refperf: Hoist function-pointer calls out of the loop paulmck
2020-06-23  0:29 ` [PATCH tip/core/rcu 07/30] refperf: Allow decimal nanoseconds paulmck
2020-06-23  0:29 ` [PATCH tip/core/rcu 08/30] refperf: Convert nreaders to a module parameter paulmck
2020-06-23  0:29 ` [PATCH tip/core/rcu 09/30] refperf: Provide module parameter to specify number of experiments paulmck
2020-06-23  0:29 ` [PATCH tip/core/rcu 10/30] refperf: Dynamically allocate experiment-summary output buffer paulmck
2020-06-23  0:29 ` [PATCH tip/core/rcu 11/30] refperf: Dynamically allocate thread-summary " paulmck
2020-06-23  0:29 ` [PATCH tip/core/rcu 12/30] refperf: Make functions static paulmck
2020-06-23  0:29 ` [PATCH tip/core/rcu 13/30] refperf: Tune reader measurement interval paulmck
2020-06-23  0:29 ` [PATCH tip/core/rcu 14/30] refperf: Convert reader_task structure's "start" field to int paulmck
2020-06-23  0:29 ` [PATCH tip/core/rcu 15/30] refperf: More closely synchronize reader start times paulmck
2020-06-23  0:29 ` [PATCH tip/core/rcu 16/30] refperf: Add warmup and cooldown processing phases paulmck
2020-06-23  0:30 ` [PATCH tip/core/rcu 17/30] refperf: Label experiment-number column "Runs" paulmck
2020-06-23  0:30 ` [PATCH tip/core/rcu 18/30] refperf: Output per-experiment data points paulmck
2020-06-23  0:30 ` paulmck [this message]
2020-06-23  0:30 ` [PATCH tip/core/rcu 20/30] refperf: Add read-side delay module parameter paulmck
2020-06-23  0:30 ` [PATCH tip/core/rcu 21/30] refperf: Adjust refperf.loop default value paulmck
2020-06-23  0:30 ` [PATCH tip/core/rcu 22/30] doc: Document rcuperf's module parameters paulmck
2020-06-23  0:30 ` [PATCH tip/core/rcu 23/30] refperf: Work around 64-bit division paulmck
2020-06-23  0:30 ` [PATCH tip/core/rcu 24/30] refperf: Change readdelay module parameter to nanoseconds paulmck
2020-06-23  0:30 ` [PATCH tip/core/rcu 25/30] refperf: Add test for RCU Tasks Trace readers paulmck
2020-06-23  0:30 ` [PATCH tip/core/rcu 26/30] refperf: Add test for RCU Tasks readers paulmck
2020-06-23  0:30 ` [PATCH tip/core/rcu 27/30] rcu-tasks: Fix synchronize_rcu_tasks_trace() header comment paulmck
2020-06-23  0:30 ` [PATCH tip/core/rcu 28/30] refperf: Rename RCU_REF_PERF_TEST to RCU_REF_SCALE_TEST paulmck
2020-06-23  0:30 ` [PATCH tip/core/rcu 29/30] refperf: Rename refperf.c to refscale.c and change internal names paulmck
2020-06-23  0:30 ` [PATCH tip/core/rcu 30/30] refscale: Change --torture type from refperf to refscale paulmck

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