OPERATING SYSTEMS M - Z

The main goal of the course is to acquire knowledge of the basic concepts related to the project of operating systems and the drawing up of programs in Linux / UNIX environment. At the end of the course students:
- will have acquired knowledge of the structure of Operating Systems, the relevant project issues and policies used for virtualization and the management of resources (CPU, main memory, mass storage, peripherals).
- will have acquired knowledge about the concepts of process and thread and their management.
- will have acquired knowledge on management techniques of mutually exclusive resources.
- will have become familiar in the interaction with the Linux shell.

Students at the end of the course will be able to write applications containing system calls for the:
- Creation and management of processes, send / signal management, interaction and communication between processes;
- Manage competition over shared resources;
- Creation of multithreaded applications.

The course is essentially based on lectures, which include the development of exercises by the teacher. The proposed exercises are addressed by the teacher through the use of computer connected to the projector. The course also includes practical exercises carried out by the students. These exercises are carried out in the University's multimedia rooms. Each student is assigned a task that must be performed on the computer. The teacher supervises the work of the students by providing the explanations and teaching aids necessary to complete the assigned tasks. The methods of carrying out the teaching described above allow the achievement of the pre-established training objectives, which include the acquisition of knowledge and the ability to apply knowledge.

UNIT 1: INTRODUCTION TO OPERATING SYSTEMS. GNU/LINUX. SYSTEM CALL. VIRTUALISATION.

• General information on the operating systems. resource management. User interface. Kernel concept.
• The GNU / Linux system. Free software and related licenses. GPL.
• Some notes on Unix and POSIX standard.
• Structure of operating systems: monolithic, microkernel, hybrid, kerenl modules, client/server.
• Concept of System calls and steps needed to achieve them. Overview of system calls of Unix/Linux, Windows.
• File System and relevant System Calls in Linux with execises.
• Operating systems for multiprocessor architectures. Virtualization. Virtual machines. Hypervisor level 1 and 2. Examples: VMware structure and Virtual Box.

UNIT 2: PROCESSES AND THREAD

• Process concept. State diagram of a process.
• Interruptions hardware and software and their management in operating systems.
• System calls for the creation and management of processes: fork (), wait (), waitpid (). The exec () family.
• Elements of system calls for the management of processes in the Windows environment.
• Signals and their management. System call kill(), signal(), alarm(), sigaction().
• Examples of programs that use all the system calls mentioned.
• Thread. General characteristics.
• Thread implementation: user space, kernel space, hybrid (with reference to the design choices of the main OS).
• Activation Scheduler, upcall. Specific data of the thread. Thread groups.
• The Pthreads library. Functions: pthread_create(), pthread_join(), pthread_exit(), pthread_detach(), pthread_attr_init ().
• Notes on Threads in Windows.
• Examples of programs that use the Pthreads library.

UNIT 3: SCHEDULING OF CPU

• CPU scheduling. Aims. Classical algorithms: FIFO, Round-Robin, Scheduling based on priorities. The problem of Starvation. Multiple queues.
• Notes on scheduling in real-time systems.
• Notes on Linux scheduling: Completely Fair Scheduler.

UNIT 4: SYNCHRONISATION.

• Critical section. Mutual exclusion with busy waiting. Semaphores and Mutex.
• Basic synchronisation probems: Producer-Consumer sharing data (sinlgle or multiple with limited size), reader-writer problem. Solutions based on semaphores and mutex.
• Mutex. Implementation in Linux using Pthread POSIX library: pthread_mutex_init, pthread_mutex_lock, pthread_mutex_trylock, pthread_mutex_unlock, pthread_mutex_destroy
• Semaphores. Implementation in Linux using System V library: semget(), semop(), semctl()
• Deadlock. Problem definition and management strategies.

UNIT 5: INTER PROCESS COMMUNICATION (IPC)

• IPC on Linux.
• Shared memory using SYSTEM V library: shmget(), shmat(), shmdt(), shmctl().
• Communication in the client-server systems: sockets using POSIX library.

For the theory: [1] Abraham Silberschatz, Peter Baer Galvin, Greg Gagne, “Operating System Concepts”, International Student Version.

or: [2] Andrew S. Tanenbaum, “I moderni sistemi operativi 4/Ed.", 2016, ISBN 9788891901019.

For the technical examples and exercitations: [3] R. Stones, N. Matthew, “Beginning Linux Programming”, 4th edition, Wrox Press, 2007.