I'm sure you've seen this as well: http://openvz.org/VSwap
but I noted these sentences:
"The sum of physpages.limit and swappages.limit limits the maximum amount of allocated memory which can be used by a container. When physpages limit is reached, memory pages belonging to the container are pushed out to so called virtual swap (vswap). The difference between normal swap and vswap is that with vswap no actual disk I/O usually occurs. Instead, a container is artificially slowed down, to emulate the effect of the real swapping. Actual swap out occurs only if there is a global memory shortage on the system."
"no actual disk I/O" -> it's in memory. And "Actual swap out occurs only if there is a global memory shortage on the system" let me still think that it actually is/should be = total memory amount...
hmm...we have something to kill hours with hehe