I've installed APC on my Gentoo LAMP server (Apache 2.2, PHP 5.2.13) and it's running fine (I see it in phpinfo()), but it's not actually doing any caching. Looking at apc.php, I can see that only 1.7% of its memory allocation is being used, which is one file of ~430kb. I'm running a CMS on the server (concrete5) which has hundreds of PHP files, so I'd expect cache utilisation to be a lot higher. Obviously it's being ignored, for some reason.
The relevant settings in php.ini are:
[apc]
apc.enabled = 1
apc.shm_size = 32
Other than that it's vanilla, as far as I know.
If it helps, here's the output of httpd -M:
Loaded Modules:
core_module (static)
authn_file_module (static)
authn_default_module (static)
authz_host_module (static)
authz_groupfile_module (static)
authz_user_module (static)
authz_default_module (static)
auth_basic_module (static)
include_module (static)
filter_module (static)
deflate_module (static)
log_config_module (static)
env_module (static)
expires_module (static)
headers_module (static)
setenvif_module (static)
version_module (static)
ssl_module (static)
mpm_prefork_module (static)
http_module (static)
mime_module (static)
status_module (static)
autoindex_module (static)
asis_module (static)
info_module (static)
suexec_module (static)
cgi_module (static)
negotiation_module (static)
dir_module (static)
actions_module (static)
userdir_module (static)
alias_module (static)
rewrite_module (static)
so_module (static)
suphp_module (shared)
Syntax OK
and php -m:
[PHP Modules]
bcmath
calendar
ctype
curl
db
dbase
domxml
exif
ftp
gd
gettext
iconv
imap
mbstring
mcrypt
mime_magic
mysql
openssl
overload
pcre
posix
session
standard
sysvsem
sysvshm
tokenizer
xml
xslt
zlib
[Zend Modules]
Any ideas would be much appreciated!
Have you added extension=apc.so somewhere in php.ini? This is exactly the most common error when trying to configure APC: not loading it.
Make sure APC setting
apc.cache_by_default = 1; Otherwise nothing will get opcode cached, only variables manually requested by code.