diff --git a/reference/apc/ini.xml b/reference/apc/ini.xml
index 364b059bd1..b530862414 100644
--- a/reference/apc/ini.xml
+++ b/reference/apc/ini.xml
@@ -31,6 +31,14 @@
   number is to allocate more memory for APC.  Barring that, the <literal>apc.filters
   </literal> ought to be used to cache fewer scripts.
  </para>
+ <para>
+  When APC is compiled with mmap support (Memory Mapping), it will use only one 
+  memory segment, unlike when APC is built with SHM (SysV Shared Memory) support 
+  that uses multiple memory segments. MMAP does not have a maximum limit like SHM 
+  does in <literal>/proc/sys/kernel/shmmax</literal>. In general MMAP support is 
+  recommeded because it will reclaim the memory faster when the webserver is 
+  restarted and all in all reduces memory allocation impact at startup.
+ </para>
  <para>
   <table>
    <title>APC configuration options</title>