diff mbox series

[v2,10/14] rcutorture: Create nocb kthreads only when testing rcu in CONFIG_RCU_NOCB_CPU=y kernels

Message ID 20230315181902.4177819-10-joel@joelfernandes.org (mailing list archive)
State Accepted
Commit 015d8863538249fc7a8f1d3ea9a9e10260adb4dd
Headers show
Series None | expand

Commit Message

Joel Fernandes March 15, 2023, 6:18 p.m. UTC 
From: Zqiang <qiang1.zhang@intel.com>

Given a non-zero rcutorture.nocbs_nthreads module parameter, the specified
number of nocb kthreads will be created, regardless of whether or not
the RCU implementation under test is capable of offloading callbacks.
Please note that even vanilla RCU is incapable of offloading in kernels
built with CONFIG_RCU_NOCB_CPU=n.  And when the RCU implementation is
incapable of offloading callbacks, there is no point in creating those
kthreads.

This commit therefore checks the cur_ops.torture_type module parameter and
CONFIG_RCU_NOCB_CPU Kconfig option in order to avoid creating unnecessary
nocb tasks.

Signed-off-by: Zqiang <qiang1.zhang@intel.com>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
---
 kernel/rcu/rcutorture.c | 6 ++++++
 1 file changed, 6 insertions(+)
diff mbox series

Patch

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 8e6c023212cb..83870c4ae1b8 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -3501,6 +3501,12 @@  rcu_torture_init(void)
 		pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
 		fqs_duration = 0;
 	}
+	if (nocbs_nthreads != 0 && (cur_ops != &rcu_ops ||
+					!IS_ENABLED(CONFIG_RCU_NOCB_CPU))) {
+		pr_alert("rcu-torture types: %s and CONFIG_RCU_NOCB_CPU=%d, nocb toggle disabled.\n",
+				cur_ops->name, IS_ENABLED(CONFIG_RCU_NOCB_CPU));
+		nocbs_nthreads = 0;
+	}
 	if (cur_ops->init)
 		cur_ops->init();