read /proc/$pid/smaps

smaps.py

#!/usr/bin/env python

import sys

def read_smaps(pidlist):
    try:
        print("PID\tRSS\tSHARED\t\tNONE_SHARED")
        mem = lambda t, f: int(f[1]) if f[0] == '%s:' % t else 0.0
        for pid in pidlist:
            filename = "/proc/%s/smaps" % pid
            with open(filename) as f:
                rss = 0.0
                shared = 0.0
                for line in f:
                    fields = line.split()
                    rss += mem('Rss', fields)
                    shared += mem('Shared_Clean', fields)
                    shared += mem('Shared_Dirty', fields)
                print("%s\t%d\t%d (%.2f%%)\t%d" %
                      (pid, rss, shared, shared/rss*100, rss - shared))

    except IOError as e:
        print(e)

if __name__ == '__main__':
    if len(sys.argv) < 2:
        print("usage: %s [pids]" % __file__)
        sys.exit(-1)

    read_smaps(sys.argv[1:])