From: Paul E. McKenney Date: Thu, 3 Nov 2011 21:56:12 +0000 (-0700) Subject: rcu: Permit RCU_FAST_NO_HZ to be used by TREE_PREEMPT_RCU X-Git-Tag: next-20111215~27^2~6^2^2~34 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=b807fbff3102bcac76ed9157d834dc20bb3d133b;p=karo-tx-linux.git rcu: Permit RCU_FAST_NO_HZ to be used by TREE_PREEMPT_RCU The new implementation of RCU_FAST_NO_HZ is compatible with preemptible RCU, so this commit removes the Kconfig restriction that previously prohibited this. Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- diff --git a/init/Kconfig b/init/Kconfig index 43298f9810fb..82b6a4c675b2 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -469,14 +469,14 @@ config RCU_FANOUT_EXACT config RCU_FAST_NO_HZ bool "Accelerate last non-dyntick-idle CPU's grace periods" - depends on TREE_RCU && NO_HZ && SMP + depends on NO_HZ && SMP default n help This option causes RCU to attempt to accelerate grace periods - in order to allow the final CPU to enter dynticks-idle state - more quickly. On the other hand, this option increases the - overhead of the dynticks-idle checking, particularly on systems - with large numbers of CPUs. + in order to allow CPUs to enter dynticks-idle state more + quickly. On the other hand, this option increases the overhead + of the dynticks-idle checking, particularly on systems with + large numbers of CPUs. Say Y if energy efficiency is critically important, particularly if you have relatively few CPUs.