[Disksim-users] (no subject)

[John Bucy]

On 6/18/06, Sriram Govindan <sgovinda at cse.psu.edu> wrote:
> Hi all,
>
> I am a new user of disksim. I have some doubts listed below.
>
> a) Instead of submitting all the disk requests in a trace file, i want to
> send the subsequent requests only when i know that the previous request is
> done with the disk, that is number of outstanding request should be one.
> In short, i want to know if the previous request has finished using the
> disk.

There is not a way to do this out of the box.  What I would do is use
the external interface to run disksim as a library and use some
lightweight threads package (gnu pth, state threads, etc) and run the
disksim event loop in one and each of your trace replays in separate
threads.  Your runtime would synchronize all of this so that the
simulated IOs in each of the trace replays would look like a blocking
call in simulated time.  Does that make sense?

> b) How to increase the size of the disk? (say barracuda disk from 2 gb to
> 40gb), i understand that it is not straight forward (just increasing the
> number of sectors)

To get anything like realistic results, it is non-trivial to do this
because all of those parameters interact in pretty subtle ways.  Also,
that barracuda model is from ~1994 IIRC -- really really old.  I know
this probably doesn't help you right now but we are going to have a
new release that will include valdiated models of much newer, larger
disks.




john