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Principles of Operating Systems Introduction and Overview Prof. Dan Connors Principles of Operating Systems Lecture 1 1 OS Staff Instructor: Prof. Dan Connors Office: MW 12-2 CS Building 320 Email: [email protected] Teaching Assistants: TA Bryan Corell Email: [email protected] Principles of Operating Systems Lecture 1 2 Course logistics and details Course Web page http://web.cs.du.edu/~dconnors/courses/comp3361 Lectures - MW 2:00-3:50 Textbook: Operating System Concepts -- 8th Edition Silberschatz and Galvin, Addison-Wesley Inc. Alternate Book Principles of Operating Systems, L.F. Bic and A.C. Shaw, Prentice-Hall/Pearson Education, 2003. ISBN 0130266116. Principles of Operating Systems Lecture 1 3 Course logistics and details Homework and Assignments ~5 written homework assignments in the quarter, and 5 programming assignments (some knowledge of C). Late homework will not be accepted. Tests Midterm - date to be announced, tentatively Week 5 in class 2:00 pm - 3:50 pm Friday John Greene Hall 316 Mar 12, 2010 - Mar 12, 2010 Principles of Operating Systems Lecture 1 4 Grading Policy Homework - 35% Midterm 30% of the final grade Final exam - 35% of the final grade Final assignment of grades will be based on a curve. Principles of Operating Systems Lecture 1 5 Lecture Schedule Week 1: • Introduction to Operating Systems, Computer System Structures, Operating System Structures Week 2 : Process Management • Processes and Threads, CPU Scheduling Week 3: Process Management • Process Synchronization Week 4: Process Management • Process Synchronization Week 5: Storage Management • Deadlocks Principles of Operating Systems Lecture 1 6 Course Schedule Week 6 - Storage Management • Midterm exam, Memory Management Week 7 - Storage Management • Memory Mangement, Virtual Memory Week 8 - I/O Systems • Virtual Memory, Filesystem Interface, Week 9 - Other topics • FileSystems Implementation, I/O subsystems Week 10 - Other topics • Case study – UNIX, WindowsNT, course revision and summary. Principles of Operating Systems Lecture 1 7 Introduction What is an operating system? Early Operating Systems Simple Batch Systems Multiprogrammed Batch Systems Time-sharing Systems Personal Computer Systems Parallel and Distributed Systems Real-time Systems Principles of Operating Systems Lecture 1 8 What is an Operating System? An OS is a program that acts an intermediary between the user of a computer and computer hardware. Major cost of general purpose computing is software. OS simplifies and manages the complexity of running application programs efficiently. Principles of Operating Systems Lecture 1 9 Goals of an Operating System Simplify the execution of user programs and make solving user problems easier. Use computer hardware efficiently. Allow sharing of hardware and software resources. Make application software portable and versatile. Provide isolation, security and protection among user programs. Improve overall system reliability error confinement, fault tolerance, reconfiguration. Principles of Operating Systems Lecture 1 10 Why should I study Operating Systems? Need to understand interaction between the hardware and applications New applications, new hardware.. Need to understand basic principles in the design of computer systems efficient resource management, security, flexibility Increasing need for specialized operating systems e.g. embedded operating systems for devices - cell phones, sensors and controllers real-time operating systems - aircraft control, multimedia services Principles of Operating Systems Lecture 1 11 Principles of Operating Systems Lecture 1 12 Abstract View of System User 1 compiler User 2 assembler User 3 ... Text editor User n Database system System and Application Programs Operating System Computer Hardware Principles of Operating Systems Lecture 1 13 Multiprogramming Use interrupts to run multiple programs simultaneously When a program performs I/O, instead of polling, execute another program till interrupt is received. Requires secure memory, I/O for each program. Requires intervention if program loops indefinitely. Requires CPU scheduling to choose the next job to run. Principles of Operating Systems Lecture 1 14 Timesharing Programs queued for execution in FIFO order. Like multiprogramming, but timer device interrupts after a quantum (timeslice). Interrupted program is returned to end of FIFO Next program is taken from head of FIFO Control card interpreter replaced by command language interpreter. Principles of Operating Systems Lecture 1 15 Timesharing (cont.) Interactive (action/response) when OS finishes execution of one command, it seeks the next control statement from user. File systems online filesystem is required for users to access data and code. Virtual memory Job is swapped in and out of memory to disk. Principles of Operating Systems Lecture 1 16 Moore’s Law- Growth in Transistor Density Defined by Dr. Gordon Moore (Intel) in the late 1960s. Predicts an exponential increase in component (transistor) density over time- a doubling time of 18 months. Does not translate directly into performance or clock frequency. Applicable to microprocessors, DRAMs, DSPs, and other microelectronics. Transistors and Clock Rate Processors got faster every 18 months (roughly 50% to 100%!) Why bother with parallel programming? Just wait a year or two. Slide Source: http://audilab.bmed.mcgill.ca/~funnell/Bacon/HW/trends.html Current Trends New Constraints Power limits clock rates Cannot squeeze more performance from ILP (complex cores) either! But Moore’s Law continues! What to do with all of those transistors if everything else is flat-lining? Power Consumption is chief concern for system architects Power-Efficiency is the primary concern of consumers of computer systems! Figure courtesy of Kunle Olukotun, Lance Hammond, Herb Sutter, and Burton Smith Emerging Multicore Processors Processor cores L2$ Shared L2$ L3$ Shared L3$ Monolithic Processor Multicore Processors Chip-multiprocessors (CMPs) • Future computer systems will integrate 10’s of multithreaded processors on a single chip die, resulting in 100’s of concurrent program threads sharing system resources • Multiple processor cores – Chip multiprocessor (CMP) – Multithreaded (SMT/MT) in each core • Lower communication costs • Purpose-built low-latency communication hardware Processor cores Shared L2$ Shared L3$ Run-time Adaptation/Optimization Shared L2$ Resource allocations PMU Data HW Alerts Shared L3$ On/off-line profile Monitoring Engine MT cores Adjusted code Operating System Static Compiler Dynamic Compiler Continuous optimization: constantly adapt system to meet current usage requirements and system characteristics System software continually and automatically adapt system resource decisions and thread execution Parallel Systems Multiprocessor systems with more than one CPU in close communication. Improved Throughput, economical, increased reliability. Kinds: • Vector and pipelined • Symmetric and asymmetric multiprocessing • Distributed memory vs. shared memory Programming models: • Tightly coupled vs. loosely coupled ,message-based vs. shared variable Principles of Operating Systems Lecture 1 23 Distributed Systems Distribute computation among many processors. Loosely coupled • no shared memory, various communication lines client/server architectures Advantages: • • • • resource sharing computation speed-up reliability communication - e.g. email Applications - digital libraries, digital multimedia Principles of Operating Systems Lecture 1 24 Real-time systems Correct system function depends on timeliness Feedback/control loops Sensors and actuators Hard real-time systems Failure if response time too long. Secondary storage is limited Soft real-time systems Less accurate if response time is too long. Useful in applications such as multimedia, virtual reality. Principles of Operating Systems Lecture 1 25 Virtual Machines Logically treats hardware and OS kernel as hardware processes processes processes Provides interface identical to underlying bare hardware. kernel kernel kernel Virtual machine hardware Creates illusion of multiple processes - each with its own processor and virtual memory