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The MDSSim program is now available at /afs/rhic/gc/MDSSim. The current
implementation does *NOT* run on Sun's java. I believe that the reason
is that Sun's thread model isn't very useful. (Sun's threads run until
they do some blocking I/O or until they yield. Microsofts timeshare
among threads of equal priority.) You should be able to run in on Visual
I will try to fix the sun problem tomorrow.
I will provide documentation linking the code to the canonical model
How to Run:
1) compile all of the *.java
2) java MDS
You will see a splash screen appear. Click on File/Edit Parameters and
change anything you wish to. Then File/Run.
Every user is represented by a separate thread.
The storage monitor is a separate thread. Right now disk memory is
infinite. This is in fact the case given 8 users and 1 event/user
available at any time.
Each tape drive has a separate thread.
Finally, there is a clock that has a separate thread to keep things
The user output shows the query, the state of the user process, fraction
of the events seen, and % of the CPU. (The current model assumes each
user has their own cpu)
The tape output shows what tape is being read, how far along you are in
a tape (it does not figure out to rewind early if it can) and whether it
is reading, skipp[ing, loading or unloading.
Here is my immediate to-do list.
1) complete the code allowing the storing and retrieval of user profiles
and event profiles. (This will allow you to test various queries against
the same data set.)
2) print summary at the end.
3) add a real disk management strategy and code.
4) Allow *really* big data sets.
5) reimplement a shared CPU scheme. (now all users have their own CPU)
6) Menu code to turn on/off the display
7) Improve the display (I need to use a fancier scheme than a
8) Javadoc the code
9) Validate the predictions on hardware
Your suggestions are appreciated.
Also, I hope to try to use Metrowerks Java compiler on the PC which
would allow the use of all of the other Java 1.1 goodies.
David R. Stampf | It has joined the choir invisible. It is an ex
Brookhaven Nat. Lab.| parrot.
Upton, NY 11973 |
1-516-344-4148 | Monty Python