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Commit d677124b authored by Frederic Weisbecker's avatar Frederic Weisbecker Committed by Paul E. McKenney
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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: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent a4fbe35a

init/Kconfig

+12 −0
Original line number Diff line number Diff line
@@ -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