I have had the same problem, plus some, when trying to guesstimate memory usage in vps servers. The caching is transparent, so free always reports zero swap. ps

I have had the same problem, plus some, when trying to guesstimate memory usage in vps servers. The caching is transparent, so free always reports zero swap. ps gives sensible numbers, but the total used memory is neither RSS nor VSZ summed. I've heard about library memory being double-counted, but I've found no way to accurately get the numbers. In the end I pretty much gave up and settled for the settings that worked. tl;dr: on vps things can be even uglier.