Learning outcomes of the course unit
The aim of the course is to provide students with the ability to understand how the operating systems manages and controls computing system resources with the objectives of efficiency and ease of use, and in particular:
- the role of the operating system as an intermediary between applications and hardware
- the need to overlap CPU and I/O activities to increase system efficiency
- the concept of process and the main models of process interaction
- the criteria and CPU scheduling algorithms for interactive systems
- the basic use of UNIX / Linux OSes and command usage
- the main system calls offered by UNIX / Linux to applications.
The main abilities to apply the knowledge and understanding listed above are:
- the analysis and evaluation of the characteristics of general-purpose operating systems
- the analysis of a simple interaction among processes in the global environment and the identification of simple forms of synchronization using semaphores
- the performance evaluation (on a given workload) of the main CPU scheduling algorithms for interactive systems
Programming skills obtained in previous courses.
Course contents summary
Introduction to Operating Systems. Batch, time-sharing and spooling systems.
Processing and I/O parallelization. The interrupt systems: device and timer interrupts.
Interrupt handling. Modelling of a simple OS and techniques for increasing
Multitasking and process model. Protection system. CPU operating modes.
I/O handling. Layered structure of OSs. Virtualization.
The process concept. Process state and descriptor. Concurrent processes.
Cooperation and competition among processes. Shared memory interaction. Mutual exclusion and critical sections. Semaphores and synchronization primitives.
Message passing interaction. Send/receive primitives, designation and
CPU scheduling and main related algorithms.
Introduction to UNIX and LINUX.
UNIX File System. File access rights. Main system commands. I/O redirection and piping. Command shell. Foreground and background command execution.
Physical organization of the file system. Process image. Program development in UNIX.
File and I/O primitives. System calls for process management: creation, execution and exit.
Interprocess communication facilities: unreliable and reliable signals, pipes, FIFOs and sockets.
Part 1 - Theory
Course introduction. Course contents and student evaluation methods. Introduction to the Linux OS and installation methods. The OS as a resource manager. OS activities for resource management. OS types and users. Proprietary and standard OSes. Brief history of computing systems and OS evolution. Batch and Time-Sharing systems. Spooling. I/O management. Polling. Overlap between I/O activities. Interrupt management.
Multiprogramming. Concept of process and process states. Process management. PCB. Process switching. OS protection and security. Context switching. System calls. OS structure with examples (UNIX, MS-DOS, Windows NT / 7). Virtualization concepts and techniques. OS kernel.
Models of process interaction. Global environment model. Tools for concurrent programming. Background on threads. Type of interaction among processes. Examples of interference. Mutual exclusion. Critical sections. Semaphores. Wait and signal primitives. Atomicity of wait / signal. Use of semaphores for producer / consumer interaction. Local environment model. Classification of designation and
synchronization alternatives. Direct and indirect designation. Synchronization for send and receive. Remote procedure calls.
Deadlock and deadlock management techniques.
Levels of scheduling. Criteria for evaluating scheduling algorithms. Basic CPU scheduling algorithms (FCFS, SJF, Priority, Round-robin, Multilevel feedback queues). Methods for evaluation. Scheduling in UNIX and Linux.
Part 2: UNIX
Introduction to UNIX. File system. Access rights to files / directories. Basic UNIX commands. Filters. I/O redirection and command piping. Running shell commands. Execution mode of commands. Wildcards. Expansion control in the command line. Scripts: syntax and examples. Laboratory practice on UNIX file system and commands.
UNIX development tools. Process image. Command line arguments and environment. System calls for I/O (open, close, read, write, lseek, etc.). Laboratory practice on I/O primitives.
System calls for process management (fork, wait, exec). Examples. Laboratory practice on primitives for process management. Optional assignment on process management.
UNIX signals. Systems calls for the unreliable signals. Issues with unreliable signals. Primitives for reliable signals. Examples. Interprocess communication with pipes. Examples. Exercises on signals and pipes. Communication with FIFOs. Laboratory practice on signals and pipes.
Socket communication. Socket types. Notes on TCP and UDP protocols. Socket systems calls. Connected sockets. Concurrent servers. Datagram sockets. Examples. The select system call. Laboratory practice on socket communication.
Sample final exams.
Lecture notes and exercises with solutions are made available on the course web
site to registered students.
*Operating Systems Concepts - 8/ed, A. Silberschatz, P. B. Galvin, G. Gagne. Wiley 2008,ISBN-13: 978-0470128725
* Advanced Linux Programming, http://www.advancedlinuxprogramming.com
- Teaching methods -
Class lectures on OS theory and UNIX/Linux usage and programming.
Lab practice on Linux PCs in the lab. Exercises on UNIX/Linux commands and shells. Programming exercises on process interaction in UNIX/Linux.
Assessment methods and criteria
Exam consists of two parts.
Part 1 - Theory: Written test with multiple open quizzes and exercises focused on basic concepts of operating systems (also administered as midterm).
Part 2 - Practice: Computer exercise on UNIX/LINUX programming and multiple process interaction. Working solution is required.
During the course an optional assignment on UNIX process management is administered, whose evaluation may be considered to increase the mark of the practice part.
Both exam parts must be passed. The final mark is obtained as average of the two partial marks. Further detailed information on the grading system will be provided during lectures.