perl and shared memory
 

I just can't get my head around shared memory.

I am writing a mail server in perl which uses Mail::SpamAssassin.
Spamassassin adds about 9Mb to the memory size of the server. The
question is, am I duplicating this 9Mb each time I fork a new server?
Or does perl use the same memory for both processes?

This is a partial output from running top:

SIZE RSS SHARE COMMAND
15888 15M 14916 SMTP Server

Since nearly all the memory used by the server is in the share column,
does that mean that the overhead in forking a process is very low? I'm
skeptical that each new server requires less than 1Mb of memory. Will
my performance increase if I use a separate SpamAssassin server, or is
this as efficient as it gets?

- Alex Hart