Reading disk usage per process

Hi,

I am using iostat and /proc/<pid>/status to determine the disk usage per process. I have a question regarding buffer cache. When I am reading a 10MB file, the counters I get show that <5MB of the file is read. Do the counters in iostat and /proc/<pid> reflect the amount of data that is *purely* read from the disk or also consider the data read from the buffer cache.

Thanks!

Check this out:

Jot Down: UNIX/Linux Recipes: Linux/Solaris: Per process accounting: Clueless which process is doing lots of I/O?

Thanks admin_xor,

This is of good help. I think the read_bytes does not consider the buffer cache. rchar does. Also, I need to consider the rate at which the count values are changing. I have a script for that.

Thanks!
Rohan