memuse measures unique physical total memory taken by a process and its children, ignoring duplicate copy-on-write pages and shared memory.
This is a solution for http://serverfault.com/questions/676335/how-measure-memory-without-copy-on-write-pages
It's a quick and dirty utility, but feel free to fork & improve.
Example:
~ » sudo ./memuse.py 15897 eugene@eugene-thinkpad
PID Commandline Frames (+unique) VMEM