From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Fri, 21 Mar 2014 20:19:05 +0100
Subject: rcu: make RCU_BOOST default on RT
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/wagi/linux-stable-rt.git
Git-commit: be70a269a5dd457a5603c5a63ba9312210a41c54
Patch-mainline: Queued in subsystem maintainer repository
References: SLE Realtime Extension
Since it is no longer invoked from the softirq people run into OOM more
often if the priority of the RCU thread is too low. Making boosting
default on RT should help in those case and it can be switched off if
someone knows better.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Daniel Wagner <dwagner@suse.de>
---
kernel/rcu/Kconfig | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/kernel/rcu/Kconfig
+++ b/kernel/rcu/Kconfig
@@ -161,8 +161,8 @@ config RCU_FAST_NO_HZ
config RCU_BOOST
bool "Enable RCU priority boosting"
- depends on RT_MUTEXES && PREEMPT_RCU && RCU_EXPERT
- default n
+ depends on (RT_MUTEXES && PREEMPT_RCU && RCU_EXPERT) || PREEMPT_RT
+ default y if PREEMPT_RT
help
This option boosts the priority of preempted RCU readers that
block the current preemptible RCU grace period for too long.