From ba49df4767d4fa5bbd2af3a51709fb81f94264ec Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Sun, 7 Oct 2012 09:26:13 -0700 Subject: [PATCH] rcu: Update RCU_FAST_NO_HZ help text The RCU_FAST_NO_HZ help text included a warning about overhead on large systems, but that issue has since been resolved. The main remaining issue with RCU_FAST_NO_HZ is increased real-time latency. This commit therefore updates the help text accordingly. Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney --- init/Kconfig | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) diff --git a/init/Kconfig b/init/Kconfig index 6fdd6e339326..b63e7982c1c6 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -582,14 +582,13 @@ config RCU_FAST_NO_HZ depends on NO_HZ && SMP default n help - This option causes RCU to attempt to accelerate grace periods - 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. + This option causes RCU to attempt to accelerate grace periods 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, thus degrading scheduling latency. - Say Y if energy efficiency is critically important, particularly - if you have relatively few CPUs. + Say Y if energy efficiency is critically important, and you don't + care about real-time response. Say N if you are unsure.