diff options
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 4 | ||||
| -rw-r--r-- | kernel/rcu/tree.c | 4 |
2 files changed, 7 insertions, 1 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index c722ec19cd00..521255f4ef13 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -4092,6 +4092,10 @@ value, meaning that RCU_SOFTIRQ is used by default. Specify rcutree.use_softirq=0 to use rcuc kthreads. + But note that CONFIG_PREEMPT_RT=y kernels disable + this kernel boot parameter, forcibly setting it + to zero. + rcutree.rcu_fanout_exact= [KNL] Disable autobalancing of the rcu_node combining tree. This is used by rcutorture, and might diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 40e5e3dd253e..d60903581300 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -100,8 +100,10 @@ static struct rcu_state rcu_state = { static bool dump_tree; module_param(dump_tree, bool, 0444); /* By default, use RCU_SOFTIRQ instead of rcuc kthreads. */ -static bool use_softirq = true; +static bool use_softirq = !IS_ENABLED(CONFIG_PREEMPT_RT); +#ifndef CONFIG_PREEMPT_RT module_param(use_softirq, bool, 0444); +#endif /* Control rcu_node-tree auto-balancing at boot time. */ static bool rcu_fanout_exact; module_param(rcu_fanout_exact, bool, 0444); |