[Linux] Any way to control swap file usage?

So I run a server on a Linux VPS. I'm having trouble with the swap file.

When the swap file is on, the server seems to use it a lot more than it needs to. Like, instead of freeing memory to load new chunks, it just dumps the old memory to the swap. It ends up using 500 megs of the swap or so for no reason, and of course it gets laggy.

When the swap file is off, everything works dandy until I try to WorldEdit anything larger than a 9x9 chunk area, then the server crashes. Otherwise nothing bad happens. Shouldn't it crash? Why would it use those extra 500 megs and not crash when it doesn't have the resources to allocate that memory?

I only turn it on for WorldEdit. Can someone explain why this happens?

 

This wouldn't be Bukkit help. I would check out some Linux forums for this problem. Unless anyone here can explain the situation and help...