From: Julia Cartwright Date: Wed, 12 Oct 2016 11:21:14 -0500 Subject: [PATCH] rcu: enable rcu_normal_after_boot by default for RT Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.25-rt16.tar.xz The forcing of an expedited grace period is an expensive and very RT-application unfriendly operation, as it forcibly preempts all running tasks on CPUs which are preventing the gp from expiring. By default, as a policy decision, disable the expediting of grace periods (after boot) on configurations which enable PREEMPT_RT_FULL. Suggested-by: Luiz Capitulino Acked-by: Paul E. McKenney Signed-off-by: Julia Cartwright Signed-off-by: Sebastian Andrzej Siewior --- kernel/rcu/update.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/kernel/rcu/update.c +++ b/kernel/rcu/update.c @@ -67,7 +67,7 @@ extern int rcu_expedited; /* from sysctl module_param(rcu_expedited, int, 0); extern int rcu_normal; /* from sysctl */ module_param(rcu_normal, int, 0); -static int rcu_normal_after_boot; +static int rcu_normal_after_boot = IS_ENABLED(CONFIG_PREEMPT_RT_FULL); module_param(rcu_normal_after_boot, int, 0); #endif /* #ifndef CONFIG_TINY_RCU */