MySQL Forums :: Performance :: how mysql process resident memory is dependent on buffer pool size

in one of my server buffer pool size is set to 6GB. when i dump high end data on the database, say 2gb data, the mysql resident memory usage shoots up to 8GB which can be seen in "TOP" command. but after completion of this data insertion even after hrs of waiting, the resident memory usage doesnt drop down. it will be stuck at 8GB.. however now if i reduce the buffer pool size from 6GB to 2 gb the resident memory drops down.. this is not the best practise... is there any solution how to de allocate this resident memory after the completion of mysql processes?? and also what is the relation between this memory and buffer pool size... any help will be deeply appreciated.. thanks

regards
vivek