From what you posted, LiteSpeed processes are using 14MB of real ram total, which is normal.
Linux/CentOS will agressively cache file read requests in the file buffer. So If all your processes leave 3G of ram "free", the kernel will use all that ram to cache file i/o. The kernel will use whatever "free/unused" process memory to cache disk requests and relinguish those ram to real processes when the need comes.
What this means that even if LiteSpeed and all your Ruby processes are only using 256MB total, the linux kernel is still free to use and display up to max memory usage.
This is normal and expected behavior.
The most important item is to check "swap" value. It should not be increasing and should hold at a very steady value, only up or down very infrequently.
Use vmstat to see some memory related stats.