Iotop displays disk I/O usage of individual process, in a way similar to top. What I really loved though is that it allows one to display the accumulated amount of I/O on any of the DISK READ, DISK WRITE, SWAPIN, and IO (overall). This is through a nifty interface:

  • You just press a on the keyboard, and it will sort the hungriest processes on top.
  • Reversing the order, you just press r.
  • If you want to sort by other colums, you just press the left/right key.

The presentation is rather busy, and it doesn't have the myriad options that top has (e.g. I can't chose to hide any of the columns I'm uninterested in), but it's more than good enough for it's specific purpose.