UMBC CMSC421 UMBC | CSEE | CMSC421 | Fall 1999 (Section 0101)

## Homework #3: Scheduling

### CMSC 421, Section 0101 (Fall 1999)

Assigned: 12 Oct 1999
Due: 19 Oct 1999 at 2:30 PM

Late homeworks will not be accepted.

Remember: your homework must be turned in online via submit.

1. Distinguish between long term and short term schedulers. What are the criteria that influence their design?
2. Schedule the following processes using FCFS, non-preemptive SJF, preemptive SJF, and round-robin (5 ms quantum). For each algorithm, show the Gantt chart for the schedule and list the average waiting time for the schedule.
Process Arrival time (ms) Burst time (ms)
P0 0 12
P1 2 5
P2 5 7
P3 7 15
P3 8 2
3. Problem 5.5 from the text.
4. Problem 5.7 from the text.
5. Your measurements of a computer system show that some processes are CPU-bound (make few, if any, I/O requests), and that the remainder of the processes are I/O-bound (make many I/O requests, but use little CPU time between them).
1. In which scheduling algorithms (FCFS, preemptive & non-preemptive SJF, RR, priority) are I/O-bound processes penalized? Explain.
2. Propose a scheduling algorithm that gives I/O-bound processes as much CPU time as they need to complete their tasks. Your solution may not depend on users identifying I/O-bound processes (they usually don't), and should be able to handle cases where a single process alternates between I/O-bound and CPU-bound periods.
6. Problem 5.10 from the text.

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Last updated 3 Dec 1999 by Ethan Miller (elm@csee.umbc.edu)