Computer Science 3

                    Operating Systems Exercise 2


Task :  To simulate and monitor the behaviour of a single process using
        the EMAS scheduling strategies.  The time-slice reference string
        of a typical process is given in file ECSC04.MOND100.  A category
        table might be:

              1    2    3    4    5    6    7    8    9
pages        24   24   24   48   48   48   72   72   72
time-slices  10   20   40   10   20   40   10   20   40
priority      1    2    3    2    3    4    3    4    5
more pages    4    5    6    7    8    9    7    8    9
less pages    1    2    3    1    2    3    4    5    6
more time     2    3    3    5    6    6    8    9    9
less time     1    1    2    4    4    5    7    7    8

    Output monitoring information during the course of the simulation
and a resume at the end.  For instance, category transitions, working
set recalculations (strobes), total page-ins (proportion execute and
read), total page-outs (proportion written to),  page*time-slice
integral,  total real-time (assuming rescheduling delay proportional
to category priority perhaps),  total cost (e.g. 1 page movement=1
time-slice in cost approx.), anything else felt relevant.

    Investigate the effect of different strategies and category tables
e.g. smaller and larger categories, more different categories.  When
does thrashing set in ? Attempt to optimise some total cost/response
time function.  Bear in mind, however, the time-shared environment
should prevent arbitrary increase in category allocations in order to
maintain overall acceptable response.  You may invent artificial
costs to make the optimisation more realistic e.g. high (allocated)
page*(allocated) time*slice costs, if you wish. Clearly there must be
some incentive to move to smaller categories.


Hand in :  a.  Description of simulation and its implementation.
           b.  Monitoring output.
          c.  Discussion of results.

Deadline :  5.00pm  Friday 16th March.