How to see top like output of n/w usage of different processes.
copied from http://sourceware.org/ml/systemtap/2006-q4/msg00022.html. just in case this machine goes down then i can look here.

also liked this blog.. will be reading content in future when have time
http://akudump.blogspot.com/


global ifxmit_p, ifrecv_p, ifxmit_b, ifrecv_b, ifdevs, ifpid, execname, user

probe netdev.transmit
{
       execname[pid()] = execname()
       user[pid()] = uid()
       ifdevs[pid(), dev_name] = dev_name
       ifxmit_p[pid(), dev_name] ++
       ifxmit_b[pid(), dev_name] += length
       ifpid[pid(), dev_name] ++
}

probe netdev.receive
{
       execname[pid()] = execname()
       user[pid()] = uid()
       ifdevs[pid(), dev_name] = dev_name
       ifrecv_p[pid(), dev_name] ++
       ifrecv_b[pid(), dev_name] += length
       ifpid[pid(), dev_name] ++
}

function print_activity()
{
       printf("%5s %5s %-7s %7s %7s %7s %7s %-15s\n",
               "PID", "UID", "DEV", "XMIT_PK", "RECV_PK", "XMIT_KB",
  "RECV_KB", "COMMAND")

foreach ([pid,dev] in ifpid-) {
printf("%5d %5d %-7s %7d %7d %7d %7d %-15s\n",
pid, user[pid], dev,
ifxmit_p[pid, dev], ifrecv_p[pid, dev], ifxmit_b[pid, dev]/1024,
ifrecv_b[pid, dev]/1024,
execname[pid])
}

print("\n")

        delete execname
       delete user
       delete ifdevs
       delete ifxmit_p
       delete ifrecv_p
       delete ifxmit_b
       delete ifrecv_b
       delete ifpid
}

probe timer.ms(5000)
{
       print_activity()
}