1 files changed, 10 insertions, 7 deletions

diff --git a/init/Kconfig b/init/Kconfig
index 717584064a7e..a3a2304fa6d2 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -582,13 +582,16 @@ 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, thus degrading scheduling latency.
-
-          Say Y if energy efficiency is critically important, and you don't
-                care about real-time response.
+          This option permits CPUs to enter dynticks-idle state even if
+          they have RCU callbacks queued, and prevents RCU from waking
+          these CPUs up more than roughly once every four jiffies (by
+          default, you can adjust this using the rcutree.rcu_idle_gp_delay
+          parameter), thus improving energy efficiency.  On the other
+          hand, this option increases the duration of RCU grace periods,
+          for example, slowing down synchronize_rcu().
+
+          Say Y if energy efficiency is critically important, and you
+                don't care about increased grace-period durations.
 
           Say N if you are unsure.