COMPSCI 110 Operating SystemsHow COMPSCI 110 will workSlide 3Objectives/ExpectationsWhat you will learnWhat’s an OS for?What is an OS?Slide 8Slide 9HW Resources to be ManagedSlide 11Examples of AbstractionsMain Issues in OS1COMPSCI 110 Operating Systems•Who - Introductions •How - Policies and Administrative Details•Why - Objectives and Expectations•What - Our Topic: Operating Systems2How COMPSCI 110 will work•It’s all explained on the webhttp://www.cs.duke.edu/~raw/cps110/index.htm•Don’t expect handouts regularly•Discussion sections–Goals: provide opportunity for interaction, questions answered, exploration of details that can’t be covered in lecture, problem-solving experiences.–Based on problems assigned from textbook–Bring your Nachos questions there3How COMPSCI 110 will work•Immediate ToDo’s:–Form project groups - email me•[email protected] subject: 110 groups•Info needed: –name for group, –desired password, –names and emails for each member of group–Begin reading textbook:•Chapter 1•Next lecture - Review of CPS 104 •First big topic, Process Mgt and Concurrency - Chapter 2 –Read introductory material on NACHOS (see “Assignments”)–Fill out and leave “Who’s who” questionnaire–Take pictures of each other•Signup sheet, associating your picture with sequential number on signup sheet (include “frame” number on camera also)•Tips for “good” photos – not too close, zoom in to fill viewfinder4Objectives/Expectations•What we want to accomplish today.•What I want you to learn in this class ...•What you can expect from me.•What I expect from you.5What you will learn•What an OS d oes . What services are provided, what functions are performed, what resources are managed, and what interfaces and abstractions are supported.•How the OS is implemented. How the code is structured. What algorithms are used.•Techniques, skills, and "systems intuition" (e.g., concurrent programming).•Peaks at current research topics.6What’s an OS fo r ?•Purposes:–To allow a computer to be SHARED among several tasks or jobs safely and efficiently.•Sequentially in time, or•In parallel (timesharing, or batch)–To make the machine easier to program–To help in porting programs between machines7What is an OS?8What is an OS?•Resource Manager of physical (HW) devices ...•Abstract machine environment. The OS defines a set of logical resources (objects) and operations on those objects (an interface on the use of those objects).•Allows sharing of resources. Controls interactions among different users.•Privileged, protected software - the kernel. Different kind relationship between OS and user code (entry via system calls, interrupts).9What is an OS?•Birthplace of system design principles: e.g., Separation of Policy and Mechanism.•Supporting role - to provide services for the target workload, not an end product itself.•Not the command interpreter and not a library of utility functions that can be linked into user programs.10HW Resources to be Managed•CPU (computation cycles)•Primary memory•Secondary memory devices (disk, tapes)•Networks•Input devices (keyboard, mouse, camera)•Output devices (printers, display, speakers)Working simultaneously. Shared among tasks. ||ism - concurrent demands from all directions.11HW Resources to be Managed•CPU (computation cycles)•Primary memory•Secondary memory devices (disk, tapes)•Networks - bandwidth for web transactions•Input devices (keyboard, mouse, camera)•Output devices (printers, display, speakers)12Examples of Abstractions•Threads or Processes (Fork)•Address spaces (Allocate)•Files (Open, Close, Read, Write)•Messages (Send, Receive)13Main Issues in OS•Structure•Concurrency and Synchronization•Extensibility, Compatibility•Communication•Sharing•Naming•Performance•Protection, Access control, Security•Reliability, Fault Tolerance•Persistence, Longevity•Scalability, Distribution•Accounting -
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