mem.py

#!/usr/bin/env python

import time
import string
import sys
import commands

def get_cpumem(pid):
# http://unix.stackexchange.com/questions/58539/top-and-ps-not-showing-the-same-cpu-result 
    if pid.isdigit():
      cmd="ps -p "+str(pid)+" -o pid,%cpu,%mem,etime,cputime"
    else:
      cmd="ps -C "+pid+" -o pid,%cpu,%mem,etime,cputime"
    psoutput=commands.getoutput(cmd).split("\n")
    if len(psoutput)<2:
      return None
    elif len(psoutput)>2:
      sys.stderr.write("warning: multiple processes called "+str(pid)+", picking first\n")
    d = psoutput[1].split()

    etime=parsetime(d[3])
    cputime=parsetime(d[4])
 
    return (float(d[1]), float(d[2]), etime,cputime)

def parsetime(timestr):
    ''' convert [[hh:]:mm:]ss into seconds '''
    timelst=timestr.split(':')
    secs=int(timelst[-1])      # seconds
    if len(timelst)>1:
      secs+=int(timelst[-2])*60   # minutes
      if len(timelst)>2:
        secs+=int(timelst[-3])*3600 #hours
    return float(secs)

if __name__ == '__main__':
    if not len(sys.argv) == 2:
        print("usage: %s PID / process name (e.g. NDPPP)" % sys.argv[0])
        exit(2)
    print("%CPU\tMEM")
    prevetime,prevcputime=None,None
    nummisses=0
 
    try:
        while True and nummisses<60:
            x = get_cpumem(sys.argv[1])
            if not x:
                sys.stderr.write("no such process: "+sys.argv[1]+"\n")
                nummisses+=1
            else:
                nummisses=0
                if prevetime==None or prevetime==x[2]:
                    cpuperc=x[0]
                    sys.stderr.write("guessing cpu perc\n")
                else:
                    # Update x[0] to be instantaneous CPU %
                    cpuperc=(x[3]-prevcputime*1.0)/(x[2]-prevetime*1.0)*100.
                prevetime=x[2]
                prevcputime=x[3]
                    
                print("%.2f\t%.2f" % (cpuperc, x[1]))
                sys.stdout.flush()
            time.sleep(1)
    except KeyboardInterrupt:
        print
        exit(0)