1CSC 4103 - Operating SystemsFall 2009Tevfik Ko!arLouisiana State UniversityAugust 25th, 2009Lecture - IIntroduction2Contact Information• Instructor: Prof. Tevfik Kosar– Office: 292 Coates (also 333 Johnston)– Phone: 578-9483– Email: [email protected]– Web: http://www.cct.lsu.edu/~kosar– Office hours: Wed & Thu, 2:00pm - 3:00pm (Or anytime by appointment)• Teaching Assistant: Qing Huag ([email protected])3Logistics• Course web page: http://www.cct.lsu.edu/~kosar/csc4103– All lecture notes will be available online– As well as homework assignments, projects and other important course information• Course mailing list: [email protected]– Important course announcements including projects, homework assignments, and exams will be sent to this mailing list– Provide me with your active email address to be added to the class mailing list4Textbooks 1: Main Text5Textbook 2: For Project (One of following)6Grading• The end-of-semester grades will be composed of:– Pop Quizzes : 10% (4-5)– Homework : 15% (5)– Projects : 20% (2)– Midterm : 25% (1) – Final : 30% (1) You are expected to attend the classes and actively contribute via asking and/or answering questions.Passive vs Active LearningPassive learning: learning through reading, hearing & seeingActive learning: learning through saying and doingAfter 2 weeks, we tend to remember: Passive learning•10% of what we read•20% of what we hear•30% of what we see (i.e. pictures)•50% of what we hear and seeActive learning•70% of what we say•90% of what we say and do7How to Become an Active Learner• Recall prior materials• Answer a question• Guess the solution first (even guessing wrong will help you to remember the right approach)• Work out the next step before you have to read on• Think of an application• Imagine that you were the professor and think about how you would give a test on the subject material so that key concepts and results will be checked.• Summarize a lecture, a set of home work or a lab in your own words concisely.89Rules• No late homework/project submissions accepted!• Exams will be closed book.• You are only responsible from material covered in the class, homework, and projects.• Academic dishonesty will be treated seriously.10What Expect to Learn?• Key Concepts of Operating Systems– Design, Implementation, and Optimization• Topics will include:– Processes, Threads and Concurrency– CPU and I/O Scheduling– Memory and Storage Management– File System Structures– Synchronization and Deadlocks– Protection and Security– Distributed Computing & Related Issues11Introduction12What is an Operating System?• A program that manages the computer hardware.• An intermediary between the computer user and the computer hardware.• Manages hardware and software resources of a computer.13Computer System Overview!A computer system consists of (bottom-up):1. hardware2. firmware (BIOS)3. operating system4. system programs5. application programs6. users14Computer System Overview1. Hardware"provides basic computing resources"CPU, memory, disk, other I/O devices2. Firmware (BIOS)"software permanently stored on chip (but upgradable)"loads the operating system during boot3. Operating system"controls and coordinates the use of the hardware among the various application programs for the various users15Computer System Overview4. System programs"basic development tools (shells, compilers, editors, etc.)"not strictly part of the core of the operating system5. Application programs"define the logic in which the system resources are used to solve the computing problems of the users"database systems, video games, business programs, etc.6. Users"people, other computers, machines, etc.16Role of an Operating System!The Silberschatz “pyramid” viewSilberschatz, A., Galvin, P. B. and Gagne. G. (2003)Operating Systems Concepts with Java (6th Edition). Abstract view of the components of a computer system17Role of an Operating System!The Tanenbaum “layered” viewTanenbaum, A. S. (2001)Modern Operating Systems (2nd Edition). A computer system consists of hardware, system programs and application programs18Role of an Operating System!The Stallings “layered & stairs” viewLayers and views of a computer system19Role of an Operating System!The Molay “aquarium” view !the only not-layered view!everything must transit through the O/S or “kernel”How are they all connected?disksprintersusersapplicationsThe kernel manages all connectionsMolay, B. (2002) UnderstandingUnix/Linux Programming (1st Edition).userspacekernel spaceKey Point• An operating system is a program that acts as an intermediary between users/applications and the computer hardware.2021Operating System Goals• From the user perspective:– Executes user programs and make solving user problems easier– Makes the computer system convenient to use• hides the messy details which must be performed• presents user with a virtual machine easier to use• From the System/HW Perspective:– Manages the resources– Uses the computer hardware in an efficient manner• time sharing: each program gets some time to use a resource• resource sharing: each program gets a portion of a resourceOS Services for Users• Program Execution– The OS loads programs and data into memory, initializes I/O devices and files, schedules the execution of programs• Access to I/O Devices– The OS hides I/O device details from applications (direct I/O access is forbidden) and offers a simplified I/O interface• Controlled Access to Files & Directories– The OS organizes data into files and directories, controls access to them (i.e. create, delete, read, write) and preserves their integrity22OS Services for Users• Communications– The OS allows exchange of information between processes, which are possibly executing on different computers• Error Detection and Response– The OS properly handles HW failures and SW errors with the least impact to running applications (i.e. terminating, retrying, or reporting)23OS Services for System/HW• Resource Allocation– The OS allocates resources to multiple users and multiple jobs running at the same time• Operation Control– The OS controls the execution of user programs and operations of I/O devices• System Access– The OS ensures that all access to resources is protected, including authorization, conflict resolution etc.•