I'm trying to fix a CentOS (5.5 x86_64) VM that we have where it become unstable due to swapping. But I did notice something: I have 10 httpd processes, and 5 of them are using 13 MB of resident memory, the other are using between 91 and 96 MB of RAM. I find it quite strange to see such differences in RAM usage. I ran a "lsof -P -p" on the processes, and I didn't see any major differences, so I'm wondering what is the best way to know what the processes are doing?