RCU: add help text for "RCU implementation type"

This patch supplies help text for the "RCU implementation type"
kernel configuration choice.

Reported-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/init/Kconfig b/init/Kconfig
index 0d0bbf2..dcc96a8 100644 (file)
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -775,6 +775,14 @@ config PREEMPT_NOTIFIERS
 choice
        prompt "RCU implementation type:"
        default CLASSIC_RCU
+       help
+         This allows you to choose either the classic RCU implementation
+         that is designed for best read-side performance on non-realtime
+         systems, or the preemptible RCU implementation for best latency
+         on realtime systems.  Note that some kernel preemption modes
+         will restrict your choice.
+
+         Select the default if you are unsure.
 
 config CLASSIC_RCU
        bool "Classic RCU"