Another big speed-up may be to pre-make all of the directories. A simple script could use CacheRoot, |CacheDirLength|, and |CacheDirLevels to create them all. Just require that this script be ran before starting a mod_disk_cache server. Or if you wanted, you could generate/check the directories in post_config.
post_config's not a bad place for that. But, I've yet to get a good handle on my thoughts for the storage mechanism that mod_disk_cache is using. My hunch so far is that it's really inefficient. (The reading of the headers one-byte at a time with the brain-dead apr_file_gets() just *killed* performance.) And, there might be a way to also save the entire response headers and body and allow a straight sendfile from that. My guess is that it'll be a slightly different cache module though - mod_cache does its best to play nice with the other filters. An option to disregard them may make sense, but we'd really have to pay attention to the Vary header then...
The Squid proxy cache requires you to create all the directories beforehand by running it with a specific switch. This save a ton of checking for and/or making directories.
Sort of dislike the fact that you must pre-create the dirs. Yet, I understand the point here. The extra stat calls might end up being harmful. Will chew on this and see if the dirs become a bottleneck or not. -- justin
