Disable APC Cache for cached files?

Question

I have a quite large website, in which there is a forum powered by phpBB. I have APC enabled with 1Gb of RAM. phpBB generates a lot of php files of cache (60 000-70 000 in my case), and they rapidly fill up APC memory. I was thinking to disable apc caching of such files through the apc.filter option. In your opinion, does it make sense?

Answer 1

I haven't run phpBB in a long time, so my answer is conditional:

• If there's actual PHP code in those cache files, there's worth to be had in caching in APC. I might go a step further and say that they're incredibly valuable to cache, since phpBB feels these files will be used often enough to have been worth caching.
• If they contain static HTML or other content that's not PHP, filter them out or convince phpBB to give them an alternate extension.

How fast are you running through your data in APC? If you're cycling through cache misses incredibly quickly, you've got a problem. If the number of misses stays constant and low over time I wouldn't worry about it. If you're storing lots of user data in APC that might be a way to shave it down. apc.php is a great way to get more details on what APC is up to, but remember it's an expensive page to load.

(have worked on several PHP sites dealing with millions to tens of millions of unique visitors per day)