[blasdel]

You can totally reduce the size of swap files on Linux, it's done the same way it is on OS X. It even has a nice syscall: swapoff(2) and a little utility that calls it swapoff(8) that comes with the standard util-linux package.

You create another new swapfile, turn it on, and then turn off the old one. The VM will copy all the old pages still in use in the old file and distribute them among the highest-priority enabled swaps with free space by round-robin. If you create the new swapfile sparsely, you don't even chew much disk space.

I discovered something hilarious in Linux's OOM-killer a while back. It has a bunch of heuristics for picking what process to kill next to save the rest: the very first one is "are any processes blocked in the swapoff syscall?"