Messages in this thread | | | Date | Wed, 10 Oct 2012 17:50:04 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH] rcu: Advise most users not to enable RCU user mode |
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On Thu, Oct 11, 2012 at 01:48:28AM +0200, Frederic Weisbecker wrote: > 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.
Queued, hopefully for 3.7, thank you!
Thanx, Paul
> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> > --- > init/Kconfig | 12 ++++++++++++ > 1 files changed, 12 insertions(+), 0 deletions(-) > > diff --git a/init/Kconfig b/init/Kconfig > index c26b8a1..89093e1 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 > -- > 1.7.5.4 >
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