KDE's KSysGuard tries to do a detailed calculation much like this if you ask for it (right-click on a process in ksysguard's process list and click "Detailed Me

KDE's KSysGuard tries to do a detailed calculation much like this if you ask for it (right-click on a process in ksysguard's process list and click "Detailed Memory Status", IIRC). This process list can be pulled directly from KRunner (Alt-F2) as well.