Background info for the request::
I have a radius server (freeradius running on Linux) that for each request needs to parse a long text file containing the allowed mac-address. From time to time, it hangs.
Since the number of requests is quite high, I want to see if there's some bottleneck due to the read access of the file (I should check also the speed of the file-parsing, but for that, I know where to check: the source file). So, I would like to monitor the read speed access of a process for a specific file, in order to figure if the process "hangs" due to the I/O limit.
What I'm not interested in: a solution for the hang of radius or debugging radius itself.
What I would like to know: a generic way to check, for a generic process, the read I/O on the disk when reads a specific file.