How to find IO time vs CPU time (Plus few more clarifications necessary)

  • I have seen the IO performance statistics. But did not get how to find the exact measure for IO time vs CPU time.

    is io_wait_time the complete time performed only doing IO and (elapsed_time - io_wait_time) only time doing cpu computation. Is (io_wait_time = read_time + write_time + read_seek_time + write_seek_time) or (read_time has both seek_time and transfer_time)

    I want to get the exact partition of time spent only on IO and time spent only on Computation and time spent doing both parallel.

    How to see if multi-threading is activated or not. (How to activate/deactivate multi-threading). How will it affect the IO vs computation performance.

    Finally, a single hard disk may have multiple heads. can this factor be used to exploit parallelism in read and write of blocks within one stxxl::disk itself.

    Thank you.