From: Frederic Weisbecker Date: Wed, 10 Oct 2012 23:48:28 +0000 (+0200) Subject: rcu: Advise most users not to enable RCU user mode X-Git-Tag: v3.7-rc1~37^2^2 X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=d677124b1fc3b2706a13e92f1b329f1ac77e5f20;p=linux-block.git rcu: Advise most users not to enable RCU user mode Discourage distros from enabling CONFIG_RCU_USER_QS because it brings overhead for no benefits yet. It's not a useful feature on its own until we can fully run an adaptive tickless kernel. Signed-off-by: Frederic Weisbecker Signed-off-by: Paul E. McKenney --- diff --git a/init/Kconfig b/init/Kconfig index c26b8a1d2b57..89093e178c27 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -451,6 +451,12 @@ config RCU_USER_QS excluded from the global RCU state machine and thus doesn't to keep the timer tick on for RCU. + Unless you want to hack and help the development of the full + tickless feature, you shouldn't enable this option. It adds + unnecessary overhead. + + If unsure say N + config RCU_USER_QS_FORCE bool "Force userspace extended QS by default" depends on RCU_USER_QS @@ -459,6 +465,12 @@ config RCU_USER_QS_FORCE test this feature that treats userspace as an extended quiescent state until we have a real user like a full adaptive nohz option. + Unless you want to hack and help the development of the full + tickless feature, you shouldn't enable this option. It adds + unnecessary overhead. + + If unsure say N + config RCU_FANOUT int "Tree-based hierarchical RCU fanout value" range 2 64 if 64BIT