Systèmes d'exploitation et cloud

This document provides an in-depth overview of fault tolerance in distributed systems. It defines essential concepts such as reliability, availability, and safety, while elaborating on different types of faults and failure modes. The methodology includes fault prevention, tolerance, detection, localization, and recovery methods using redundancy, error masking, and error correction techniques. The findings underscore the importance of implementing robust error handling mechanisms to ensure system reliability and functionality under adverse conditions.

The study addresses the optimization of scheduling independent tasks on heterogeneous processors to minimize makespan through load balancing. Key metrics include the weighted processor load (CHP) and the maximum load across processors (M). Two primary scheduling principles are discussed, alongside three iterative algorithms (LS, SPT, LPT) each with two variations based on the given principles. Improvements are proposed via heuristic adjustments that reassign tasks between processors to achieve better load distribution. Comparative analyses establish the superiority of Principle 2 over Princ...

The document focuses on task scheduling and the dependencies involved between tasks in a computational context. It categorizes dependencies into three types: producer-consumer dependencies, consumer-producer (anti-dependencies), and producer-producer (output dependencies). Specific examples are provided to illustrate each type of dependency alongside respective precedence rules. Additionally, a remark highlights the sequential order of program execution governing dependency precedence.

This document explores the methodology of task scheduling by structuring dependencies into a sequence. It defines input-output relationships of tasks, identifies dependencies categorized as producer-consumer, consumer-producer, or producer-producer. Redundant dependencies are removed through transitivity. The approach concludes with a dependency graph identifying critical tasks and their optimal order.

The document analyzes task scheduling using precedence and execution trees for associative expressions. Two versions of scheduling, early (Version 1) and late (Version 2), are compared through sequential time (T1) and parallel efficiencies (S3, E3 for Version 1; S2, E2 for Version 2). Version 2 is shown to outperform Version 1 based on efficiency comparisons. The document concludes that late task scheduling reduces processing inefficiencies.

The text explains the historical and philosophical principles behind the Free Software License (FS) and its evolution into the General Public License (GPL), emphasizing freedoms like usage, modification, and redistribution. It highlights the concept of 'copyleft,' designed to ensure software remains free by mandating derivative works adhere to the same licensing structure. Examples of free software tools such as GNU, GIMP, and Audacity are mentioned. Additionally, it provides an overview of command-line basics, types of shell interpreters, and internal vs external commands with examples.

This document explores the management of processes in Unix/Linux operating systems, starting with an introduction to system calls and the POSIX standards. It details the structure and management of processes, covering concepts such as process creation using `fork()`, process control using system calls like `exec` and `wait`, and communication through shared resources. It also analyzes process termination, signaling mechanisms, and the use of the standard C library for executing commands. Examples and exercises are provided for hands-on understanding.

ISTIC 2018-2019 Communication entre processus par tubes anonymes Amira BELHEDI belhedi. amira@yahoo. fr R f rence livre Programmation syst me en C sous Linux Signaux, processus, threads, IPC et sockets Communication par les tubes (pipes) Tube de communication: canal ou tuyau (en anglais pipe) dans lequel un processus peut crire des donn es (producteur, crivain ou r dacteur) et un autre processus peut les lire (consommateur).