Module 1 - Part 2.pdf

Sudan University of Science and Technology College of Engineering Operating System Module 1 – Part 2 Introduction Dr. Isam Abdelnabi Osm...

Sudan University of Science and Technology College of Engineering Operating System Module 1 – Part 2 Introduction Dr. Isam Abdelnabi Osman Parallel Systems Multiprocessor systems with more than on CPU in close communication. Tightly coupled system – processors share memory and a clock; communication usually takes place through the shared memory. Advantages of parallel system: Increased throughput Economical Increased reliability graceful degradation fail-soft systems Dr. Isam Abdelnabi Osman 14 1  Parallel Systems (Cont.) Symmetric multiprocessing (SMP) Each processor runs and identical copy of the operating system. Many processes can run at once without performance deterioration. Most modern operating systems support SMP Asymmetric multiprocessing Each processor is assigned a specific task; master processor schedules and allocated work to slave processors. More common in extremely large systems Dr. Isam Abdelnabi Osman 15 Symmetric Multiprocessing Architecture 16 Dr. Isam Abdelnabi Osman 2  Distributed Systems Distribute the computation among several physical processors. Loosely coupled system – each processor has its own local memory; processors communicate with one another through various communications lines, such as high-speed buses or telephone lines. Advantages of distributed systems. Resources Sharing Computation speed up – load sharing Reliability Communications Dr. Isam Abdelnabi Osman 17 Distributed Systems (cont) Requires networking infrastructure. Local area networks (LAN) or Wide area networks (WAN) May be either client-server or peer-to-peer systems. Dr. Isam Abdelnabi Osman 18 3  General Structure of Client-Server 19 Dr. Isam Abdelnabi Osman Clustered Systems Clustering allows two or more systems to share storage. Provides high reliability. Asymmetric clustering: one server runs the application while other servers standby. Symmetric clustering: all N hosts are running the application. Dr. Isam Abdelnabi Osman 20 4  Real-Time Systems Often used as a control device in a dedicated application such as controlling scientific experiments, medical imaging systems, industrial control systems, and some display systems. Well-defined fixed-time constraints. Real-Time systems may be either hard or soft real-time. Dr. Isam Abdelnabi Osman 21 Real-Time Systems (Cont.) Hard real-time: Secondary storage limited or absent, data stored in short term memory, or read-only memory (ROM) Conflicts with time-sharing systems, not supported by general-purpose operating systems. Soft real-time Limited utility in industrial control of robotics Useful in applications (multimedia, virtual reality) requiring advanced operating-system features. Dr. Isam Abdelnabi Osman 22 5  Handheld Systems Personal Digital Assistants (PDAs) Cellular telephones Issues: Limited memory Slow processors Small display screens. Dr. Isam Abdelnabi Osman 23 Computing Environments Traditional computing Web-Based Computing Embedded Computing Dr. Isam Abdelnabi Osman 24 6