Problem Set $02$: Processes and Threads

CSci $430$: Operating Systems

Overview

In this written problem set you will be given some exercises in order to help expand your understanding of the concept of processes and threads and what functions they perform in a modern operating system.

All modern multiprogramming operating systems, from single$-$user systems to mainframes and clustered servers are built around the concept of processes and threads. Answer the following questions about processes, process state transitions, threading and multiprogramming. Provide adequate written description and work to support your arguments and conclusions in the answers to your questions. Show all work.

Learning Objectives

Better understand processes, process preemption, process modes, etc.

Understand process states and process state transitions, and what purpose they serve in a multiprogramming operating system.

Explore thread concepts, learn what responsbilities threads handle in an OS and which aspects are part of processes.

Begin to understand issues of thread concurrency.

Submission

All work must be submitted by the announced due date for this assignment to guarantee you will receive an evaluaiton for your work. A submission folder has been created in our MyLeoOnline class shell for this assignment. Submit all work as an attachment to the submission folder. Ensure your work is readible and neatly presented. Electronic work can be submitted in $.$doc, $.$odt, $.$pdf or other commonly used electronic document formats. Handwritten work can be scaned or photographed, though it is preferrable if you collect scans into a single document like a $.$pdf to submit them. If scanning handwritten work, it is your responsibility to ensure it can be read and understood sufficiently, otherwise the submission may not be graded.

$1$

$1$ Process Priority and Swapping

Consider the state transition diagram of Figure $3\mathrm{.}9$b from our class textbook. Suppose that it is time for the OS to dispatch a process and that there are processes in both the Ready state and the Ready$/$Suspend state, and that at least one process in the Ready$/$Suspend state has higher scheduling priority than any of the processes in the Ready state. Two extreme policies are as follows $(1)$ Always dispatch from a process in the Ready state, to minimize swapping, and $(2)$ always give preference to the highest$-$priority process, even though that may mean swapping when swapping is not necessary.

Questions

Suggest an intermediate policy that tries to balance the concerns of priority and performance. Compare your suggestion to the two extremes described, and analyze how swapping and performance is impacted.