Shared Dirty memory of Apache parent process

Hi,
   I am new to mod perl environment so this may looks naive.
  Recenlty I observed my apache processes are getting huge.. When I tried
to dig this down I found apache parent process (rss memory , mainly shared
dirty) itself is increasing with number of requests it is serving, so when
everytime it is creating a new child it is sharing all its memory with
childs and they are getting even more bigger and so on..
 I am thinking this might be one reason. I decalred a global variable in
apache startup (so it'll be shared on across all childs), this variable
will be loaded with huge DB data in one of perl modules(after request
comes). Will this increase shared dirty of parent ? (After child writes
into it, it will no longer shared between parent and child., and parent
shared dirty should get decreased .. right ?)
 At start parent is only 100MB and after some days it's going above 250MB
and so childs are going above 400M..
Can anybody help ?

Thanks,
Rao.