I think I am wrong. I now think top's 'SHR' isn't the "total amount of virtual memory shared", it's "amount of RES which is shared". (Hmm...but my test could be

I think I am wrong. I now think top's 'SHR' isn't the "total amount of virtual memory shared", it's "amount of RES which is shared". (Hmm...but my test could be conflating "RES" memory with "allocated" VM (memory which is backed by something, be it swap or RAM). So you can indeed substract SHR from RES to get a feel for per-proc RES. (But that 'feel' doesn't tell you how many procs that SHR is shared with, and worse, which ones. If firefox fork()d then all it firefox-specific code pages would contribute to SHR, but you'd really want to account for them in the "firefox application"). (I'd also definitely expect chunks of libc and gtk libs to not be resident, primarily because they're code pages containing only code paths not yet chased on this box. And only one app has used those pages, do you really want to call that 'shared'?)