From: dgaudet
This is an experimental module and should be used with
- care. It maps a list of statically configured files (via
+ care. You can easily create a broken site using this module, read this
+ document carefully.
+
This mmap()ing is done once at server start or restart, only. So whenever
one of the mapped files changes on the filesystem you have to
- restart the server by at least sending it a HUP or USR1 signal. To
+ restart the server by at least sending it a HUP or USR1 signal (see the
+ Stopping and Restarting documentation). To
reiterate that point: if the files are modified in place without
restarting the server you may end up serving requests that are completely
bogus. You should update files by unlinking the old copy and putting a new
copy in place. Most tools such as Summary
mod_mmap_static
maps a list of statically configured files (via
MMapFile
directives in the main server configuration) into
- memory through the system call mmap()
. Although this system
- call is not available on every platform, most of the modern Unix derivates
- provide it. At least those ones conforming to the POSIX.4 definition. The
- size of the mapable files usually has to be less then 2GB. But this is no
- real restriction for documents on a webserver.
+ memory through the system call mmap()
. This system
+ call is available on most modern Unix derivates, but not on all. There
+ are sometimes system-specific limits on the size and number of files that
+ can be mmap()d, experimentation is probably the easiest way to find out.
rdist
and mv
do
this. The reason why this modules doesn't take care of changes to the files
is that this check would need an extra stat()
every time which
- is a waste and against the intend of I/O reduction.
+ is a waste and against the intent of I/O reduction.
Directives
@@ -107,9 +109,11 @@
match the filesystem path Apache's URL-to-filename translation handlers
create. We cannot compare inodes or other stuff to match paths through
symbolic links etc. because that again would cost extra stat()
- system calls which is not acceptable.
+ system calls which is not acceptable. This module may or may not work
+ with filenames rewritten by mod_alias
or
+ mod_rewrite
... it is an experiment after all.
Notice: You cannot use this for speeding up CGI programs or other files which are served by special content handlers. It can only be used for @@ -122,6 +126,15 @@ MMapFile /usr/local/apache/htdocs/index.html +
+ Note: don't bother asking for a for a MMapDir
directive which
+ recursively maps all the files in a directory. Use Unix the way it was
+ meant to be used. For example, see the
+ Include directive, and consider this command:
+
++ find /www/htdocs -type f -print | sed -e 's/.*/mmapfile &/' > /www/conf/mmap.conf +