Configuring mod_mem_cache to only cache certain content types and finding out what is cached

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http://serverfault.com – I've installed Apache's mod_mem_cache on a server that serves multiple websites. I needed to install it in a hurry as I had a massive traffic spike and was firefighting. It has improved performance massively and all of my sites seem to be serving the correct content, all is well, but I have two questions: How do I restrict the content types that are cached? Ideally I'd like to cache just css|js|jpg. I tried a <FilesMatch> within the mod_mem_cache.conf but that didn't work. Is there any way to see which files are in the cache at any point? (HowTos)