Looking at the output of the unix command 'top', you can see:
PID USER PRI NI SIZE RSS SHARE STAT LIB %CPU %MEM
TIME COMMAND
18983 nobody 5 0 4564 4564 2848 S 0 4.7 0.4 0:52 httpd
18633 nobody 3 0 4552 4552 2904 S 0 2.0 0.4 0:56
httpd
The information in the "SIZE" and "SHARE" collumns are what we
are most interested in. SIZE is the memory used by the apache
process, while SHARE is the shard memory it uses. Based on that, fill
in the information below. The total RAM on the server is the only
other number you'll need. Ideally, this would be the total RAM installed in the system, minus what the operating system is using at any given time (which is often hard to figure out- ballpark for linux would be 64mb)