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 <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

1 files changed, 7 insertions, 8 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.
-
-          Say Y if energy efficiency is critically important, particularly
-                if you have relatively few 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, and you don't
+                care about real-time response.
 
           Say N if you are unsure.