* doc/apt.conf.5.xml:

  - add and document APT::Cache-{Start,Grow,Limit} options for mmap control

2 files changed, 17 insertions, 4 deletions

diff --git a/doc/apt.conf.5.xml b/doc/apt.conf.5.xml
index 39e2c8e6b..7b7290794 100644
--- a/doc/apt.conf.5.xml
+++ b/doc/apt.conf.5.xml
@@ -199,9 +199,20 @@ DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
      anything that those packages depend on.</para></listitem>
      </varlistentry>
 
-     <varlistentry><term>Cache-Limit</term>
-     <listitem><para>APT uses a fixed size memory mapped cache file to store the 'available'
-     information. This sets the size of that cache (in bytes).</para></listitem>
+     <varlistentry><term>Cache-Start, Cache-Grow and Cache-Limit</term>
+     <listitem><para>APT uses since version 0.7.26 a resizable memory mapped cache file to store the 'available'
+     information. <literal>Cache-Start</literal> acts as a hint to which size the Cache will grow
+     and is therefore the amount of memory APT will request at startup. The default value is
+     20971520 bytes (~20 MB). Note that these amount of space need to be available for APT
+     otherwise it will likely fail ungracefully, so for memory restricted devices these value should
+     be lowered while on systems with a lot of configured sources this might be increased.
+     <literal>Cache-Grow</literal> defines in byte with the default of 1048576 (~1 MB) how much
+     the Cache size will be increased in the event the space defined by <literal>Cache-Start</literal>
+     is not enough. These value will be applied again and again until either the cache is big
+     enough to store all information or the size of the cache reaches the <literal>Cache-Limit</literal>.
+     The default of <literal>Cache-Limit</literal> is 0 which stands for no limit.
+     If <literal>Cache-Grow</literal> is set to 0 the automatic grow of the cache is disabled.
+     </para></listitem>
      </varlistentry>
 
      <varlistentry><term>Build-Essential</term>
diff --git a/doc/examples/configure-index b/doc/examples/configure-index
index fdec32c2c..26fb53fec 100644
--- a/doc/examples/configure-index
+++ b/doc/examples/configure-index
@@ -95,7 +95,9 @@ APT
   Clean-Installed "true";
   Immediate-Configure "true";      // DO NOT turn this off, see the man page
   Force-LoopBreak "false";         // DO NOT turn this on, see the man page
-  Cache-Limit "4194304";
+  Cache-Start "20971520";
+  Cache-Grow "1048576";
+  Cache-Limit "0";
   Default-Release "";
 
   // consider Recommends, Suggests as important dependencies that should