This module provides mmap()ing of a statically configured list of frequently requested but not changed files.
Source File: mod_mmap_static.c
Module Identifier: mmap_static_module
Compatibility: Available in Apache 1.3 and later.
This is an
module and should be used with
care. You can easily create a broken site using this module, read this
maps a list of statically configured files (via
directives in the main server configuration) into
memory through the system call
. 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.
This mmap()ing is done once at server start or restart, only. So whenever
one of the mapped files changes on the filesystem you
restart the server by at least sending it a HUP or USR1 signal (see the
Stopping and Restarting
reiterate that point: if the files are modified
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
this. The reason why this modules doesn't take care of changes to the files
is that this check would need an extra
every time which
is a waste and against the intent of I/O reduction.
Override: Not applicable
Compatibility: Only available in Apache 1.3 or later
directive maps one or more files (given as
whitespace separated arguments) into memory at server startup time. They
are automatically unmapped on a server shutdown. When the files have changed
on the filesystem at least a HUP or USR1 signal should be send to the server
to re-mmap them.
Be careful with the
arguments: They have to literally
match the filesystem path Apache's URL-to-filename translation handlers
create. We cannot compare inodes or other stuff to match paths through
because that again would cost extra
system calls which is not acceptable. This module may or may not work
with filenames rewritten by
... 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 regular files which are usually served by the Apache core content handler.Example:
: don't bother asking for a for a
recursively maps all the files in a directory. Use Unix the way it was
meant to be used. For example, see the
directive, and consider this command:
find /www/htdocs -type f -print \ | sed -e 's/.*/mmapfile &/' > /www/conf/mmap.conf