documentation: Add pointer to percpu-ref for RCU and refcount
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
diff --git a/Documentation/RCU/rcuref.txt b/Documentation/RCU/rcuref.txt
index 141d531..613033f 100644
--- a/Documentation/RCU/rcuref.txt
+++ b/Documentation/RCU/rcuref.txt
@@ -1,5 +1,14 @@
Reference-count design for elements of lists/arrays protected by RCU.
+
+Please note that the percpu-ref feature is likely your first
+stop if you need to combine reference counts and RCU. Please see
+include/linux/percpu-refcount.h for more information. However, in
+those unusual cases where percpu-ref would consume too much memory,
+please read on.
+
+------------------------------------------------------------------------
+
Reference counting on elements of lists which are protected by traditional
reader/writer spinlocks or semaphores are straightforward: