I usually use Nethogs to see the network bandwidth per process. However, Nethogs won't see the PID of the processes generating some NFS traffic, and as a result they are aggregated over one single line with
? as PID:
Why does that happen and is there any way to circumvent it so that I can see NFS bandwith per PID?
I use NFSv3 on Ubuntu 12.04 (client).