1ECE397A – Operating SystemsOverview Welcome!  Instructor: Professor Csaba Andras Moritz, [email protected] Class webpage: http://www.ecs.umass.edu/ece/andras/courses/ECE397_S2005 Instructor’s webpage: http://www.ecs.umass.edu/ece/andras Office: Knowles 309H Phone number in office: (413) 545 2442 Secretary: Chris Langlois TA is Yao Guo (my PhD student) [email protected] Office hours: TuTh 11AM-12:15PM (after the class) Any other time by appointment (please send email or ask after lecture) TA office hours will be posted on the webOverview Course (contd.) 4-5 homeworks, 4-5 projects/labs in Java/C (30%) Note that homeworks will not have to be handed in (but you can if you want to have them graded) Labs will be checked by instructor and TA 2 exams and pop quizzes (60%) Several questions from homeworks 10% grade is from pop quizzes 20% from first exam 30% from final exam Class attendance/participation (10%)  All class related information will be put on the web, check the class webpage regularly. Acknowledgements: material leveraged from Silberschatz, Galvin, and Gagne.2How do I spend my time? BlueRISC – startup company developing microprocessor technology Research Nanoelectronics and nanoarchitectures Low power microprocessors (sponsored by NSF grants) Multiprocessor-on-chip architectures (NSF) Security tradeoffs in sensor networks (Darpa) Teaching  OS and Architecture (graduate level) Example of service in the community  Associate editor of IEEE Transactions on Computers Tutorial Chair Parallel Architectures and Compilation (PACT 2003) Chair Boston Area Architects Conference 2004 and 2005  Various committees  Advising students Graduate students pursuing PhD and MS degrees Undergraduate students interested in computer architectureChapter 1: Introduction What is an Operating System? Mainframe Systems (OS390, z/OS, Linux for S/390, available on G5, G6 and Multiprise 3000 procs. ) Desktop Systems (WinNT,Me,2000,XP, Linux, Solaris, BeOS, OS2-Warp, MAC OS X …) Multiprocessor Systems (FreeBSD SMP, Raw OS,..) Distributed Systems – Middleware (CORBA, .NET, J2EE) Clustered System (SGI CXFS 2.0, TeraGrid project) Embedded Systems  Real -Time Systems (RTOS, lots of specialized OS) Handheld Systems (Pocket PC2002, PalmOS)3What is an Operating System? A software that acts as an intermediary between a user of a computer and the computer hardware. Operating system goals: Execute user programs and make solving user problems easier. Make the computer system convenient to use. (G)UI interface. Manage hardware resources Use the computer hardware in an efficient manner.Computer System Components Hardware – provides basic computing resources (CPU, cache, memory, disk, I/O devices). Operating system – controls and coordinates the use of the hardware among the various application programs for the various users. Applications programs define the ways in which the system resources are used to solve the computing problems of the users (compilers, database systems, video games, business programs). Users (people, other computers).4Abstract View of System ComponentsOperating System Definitions Resource allocator – manages and allocates resources. Why do we need to manage resources? Control program – controls the execution of user programs and operations of I/O devices .  Why can’t we have all IO controls implemented in the applications directly? Kernel – the one program running at all times (all else being application programs).  Why do we need a kernel?5Mainframe Systems Reduce setup time by batching similar jobs Automatic job sequencing – automatically transfers control from one job to another. First rudimentary operating system. Resident monitor initial control in monitor  control transfers to job  when job completes control transfers pack to monitorMemory Layout for a Simple Batch System6Multi-programmed Batch SystemsSeveral jobs are kept in main memory at the same time, and the CPU is multiplexed among them. OS Features Needed for Multiprogramming I/O routine supplied by the system. Memory management – the system must allocate the memory to several jobs. CPU scheduling – the system must choose among several jobs ready to run. Allocation of devices.7Time-Sharing Systems–Interactive Computing  The CPU is multiplexed among several jobs that are kept in memory and on disk (the CPU is allocated to a job only if the job is in memory). A job swapped in and out of memory to the disk. On-line communication between the user and the system is provided; when the operating system finishes the execution of one command, it seeks the next “control statement” from the user’s keyboard. On-line system must be available for users to access data and code.Desktop Systems Personal computers – computer system dedicated to a single user. I/O devices – keyboards, mice, display screens, small printers. User convenience and responsiveness. Can adopt technology developed for larger operating system’ often individuals have sole use of computer and do not need advanced CPU utilization of protection features. May run several different types of operating systems (Windows, MacOS, UNIX, Linux)8Parallel 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 systemsParallel Systems (Cont.) Symmetric multiprocessing (SMP) Each processor runs an 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 systems9Symmetric Multiprocessing ArchitectureDistributed 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