Operating Systems M - Z

Knowledge and understanding: Upon completion of the course, the student will have acquired the knowledge of the basic concepts inherent to the design of operating systems and the writing of programs that exploit System Calls in Linux / UNIX environment. At the end of the course the 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.

Applying knowledge and understanding: at the end of the course the students  will be able to write applications containing system calls for the: creation and management of processes and threads, management of files, signal management, interaction and communication between processes, manage competition over shared resources and creation of multithreaded applications.

Making judgements. On completion of the course, the student will be able to choose a suitable software solution based on Linux API  for each of the subjects treated inside the course.

Communication skills. On completion of the course, the student can communicate his conclusions and recommendations about design and use of operating systems  with the argumentation of the knowledge and rationale underpinning these, to both specialist and non-specialist audiences clearly and unambiguously.

Learning skills. On completion, the student will be able to continue to study in a manner that may be largely selfdirected or autonomous.

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 . 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.

• Overview of  Operating Systems. Resource management. User interface. Kernel concept.
• Some notes on Unix and POSIX standard.
• Structure of operating systems: monolithic, microkernel, hybrid, kerenl modules.
• Concept of System Calls and relevant realization.
  
• Overview of Linux and relevant system calls.
• File System and relevant System Calls in Linux  with execises.
• Virtualization. Virtual machines. Hypervisor level 1 and 2. Example: Virtual Box.

UNIT 2: PROCESSES AND THREAD

• Process concept. States of a process.
• Interruptions hardware and software and their management in operating systems. Context Switching
  
• System calls for the creation and management of processes: fork (), wait (), waitpid (). The exec () family. Examples of programs that use all the system calls mentioned.
• Signals and their management. System calls kill(), sleep(), pause(), alarm(), wait(), 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).
• The Pthreads library. Functions: pthread_create(), pthread_join(), pthread_exit(), pthread_detach(), pthread_attr_init ().
• 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. Scheduling algortihms based on preemption. The problem of Starvation. Multiple queues.
• 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”, Pearson.

or: [2] Andrew S. Tanenbaum, “I moderni sistemi operativi", Pearson.

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

The exams are fixed in agreement with the CdS in compliance with the procedures established by the academic calendar.

Reservations are required through the University portal. The closing date for reservations is usually fixed a few days before the exam, in order to allow the teacher to book the computer rooms of adequate capacity for the number of registered students.

The exam consists of a written test and oral test.

The written test is made up by two sections. The first section is relevant to the realization of one or more programs in C language using the system calls studied inside the course; for  this reason it requires the use of a computer made available to the students by the university. The second section consists of one or more theoretical questions. The first section allows to achieve a total value of 18/30 points; the second sections allows to achieve a total value of 12 /30 points. The written test, lasting 3 hours,  is passed if the sum of the two values is greater than or equal to 18/30. On the site available on Studium (www.studium.it) a template of the written test that specifies both the types of sections and the relative points, is present.

The oral test is optional and can only be held in the same session in which the written test was passed. The oral exam focuses on the theoretical topics discussed in class.

To ensure equal opportunities and in compliance with current laws, interested students may request a personal interview in order to plan any compensatory and/or dispensatory measures based on educational objectives and specific needs. Students can also contact the CInAP (Centro per l’integrazione Attiva e Partecipata - Servizi per le Disabilità e/o i DSA) referring teacher within their department.