monitoring per-process disk io

[R.P. Aditya]

I'm trying to monitor, over the long-term, per-process disk IO (a
counter of bytes read and written per pid would be ideal).

I currently monitor per pid cpu and memory usage using the SNMP
Host-Resources MIB, however I don't see any oids for io (disk or
otherwise) per oid.

The closest I've come to finding what I want -- per-process disk IO
stats -- is the Linux tool dstat -- something like "screenshot 3" at:

  http://dag.wieers.com/home-made/dstat/

which is the output of:

  dstat -c --top-cpu -d --top-bio --top-latency

would be good...iostat, vmstat don't give that sort of info...

any suggestions or hints? 

Thanks,
Adi