CS 537 - Quiz #5

	UNIVERSITY OF WISCONSIN-MADISON Computer Sciences Department
CS 537 Spring 2000		A. Arpaci-Dusseau
	Quiz #5: Wednesday, March 22

Name: Student ID #:

Solaris Time-Sharing Scheduler

Problem 1: Solaris Dispatch Table (80 pts)

To answer this problem, use the dispatch table that is appended at the end of the quiz (it is identical to the default dispatch table in Solaris).

a) Consider a process that is at priority 49.

How long is the time-slice of this process?
When the process consumes its time-slice, what will its new priority be?
If the process is neither sleeping nor running when the 1 second update time expires, what will its new priority be?
If the process is sleeping when the 1 second update timer expires, what will its new priority be?

b) Consider a workload containing only a single process. Assume that this process is completely CPU-bound. Draw a timeline showing the priority of that process for the first 600ms of its lifetime. In all of your timelines, clearly show both the priority of the job and the time at which the priority of the process changes. Assume that the 1 second update timer does not run in this interval. (Hint: Processes start at priority 29.)

c) Consider a new workload containing a single process; this process repeatedly computes for 20ms and then sleeps for 1000ms. Draw a timeline showing the priority of this process for 3 iterations of its compute/sleep cycle. You can assume that the 1 second update timer begins its cycle at the same time the process enters the system (i.e., the timer expires 1 second after the process begins executing).

d) Consider a dispatch table where the fourth column contains all 1's (instead of all 0's). Show the priority timeline for the workload of question c) with this modified dispatch table.

Problem 2: Required Accounting (20 points)

List three pieces of accounting information that must be tracked and recorded for each process when implementing the functionality of the Solaris Time-sharing Scheduler. (Do not include any items that are simply pointers to other data structures).