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 abilities to apply the knowledge and understanding listed above are in particular:
- 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
- the analysis of the interactions among UNIX processes, the identification of required interprocess communication primitives and system calls, and the implementation of C programs that take advantage of them
Course contents summary
Introduction to Operating Systems. Batch, time-sharing and spooling
Processing and I/O parallelization. The interrupt systems: device and
Interrupt handling. Modelling of a simple OS and technique for increasing
Multitasking e process model. Protection system. CPU operating modes.
I/O handling. Layered structure of OSs. Virtualization.
Concept of process. Process state and descriptor. Concurrent processes.
Cooperation and competition among processes. Shared memory
interaction. Mutual exclusion and critical sections. Semaphores e
Message passing interaction. Send/receive primitives, designation and
CPU scheduling and main 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
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.
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. (4 hours)
Multiprogramming. Concept of process and possible 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 (5 hours)
Models of process interaction. Global environment model. Tools for concurrent programming. Some 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. (5 hours)
Deadlock and management techniques (2 hours)
Levels of scheduling. Criteria for algorithm evaluation. CPU scheduling algorithms (FCFS, SJF, Priority, Round-robin). Methods for evaluation. UNIX scheduling. Overview of real-time scheduling. (3 hours)
An 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. (4 hours)
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 (4 hours)
System calls for process management (fork, wait, exec). Examples. Laboratory practice on primitives for process management. Presentation of the optional assignment on process management. (4 hours)
UNIX signals. Systems calls for the unreliable signals. Issues with unreliable signals. Primitives for reliable signals. Examples. Inter-process communication with pipes. Examples. Exercises on signals and pipes. Communication with FIFOs. Laboratory practice on signals and pipe (5 hours)
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 (4 hours)
Sample final exams. (2 hours).
Class lectures on OS theory and UNIX/Linux usage and programming.
Lab practice on Linux PCs at the “Laboratorio Informatica di base”
Exercises on UNIX/LINUX commands and shells. Programming exercises on process
interaction under UNIX/LINUX.
Assessment methods and criteria
Written examination on the theory of Operating Systems (Part I of the
course) or midterm exam.
Computer exercise on UNIX/LINUX system programming.
Optional programming assignment on Linux process management.
Final grade is weighted on theory (40%) and UNIX (60%) grades.