Course Description OS Introduction

1. Lecture 1 Course DescriptionOS Introduction CS5002 Operating Systems Dr. Jose M. Garrido • Class • Will • Start • Momentarily…

2. Course Description Course Description: • This is one of three foundation courses covering programming/data structures, computing and network systems, and operating systems. • This second course (CS6502) will focus on operating systems.  Prerequisites: Permission of MSACS director. 

3. Course Description Textbook: Principles of Modern Operating Systems. J. M. Garrido and R. Schlesinger. Jones and Bartlett Pub. 2008. ISBN 0-7637-3574-4.

4. Course Description Course Objectives: • Cover operating systems concepts and principles. Learning Outcomes: See course web page for syllabus

5. Coursework • Hands-on will involve assignments using discrete-event object-oriented simulation, with the Psim3 package. • This facilitates the study of models of various aspects of operating systems, to determine their dynamic behavior, and to determine the performance measures. • For the assignments, students need to login to "cs3.kennesaw.edu". The Psim3 library for the Linux system is installed on the CS3 server.

6. Course Outline • See course syllabus on Web page

7. Special Dates • See course syllabus on web page

8. Class Format • Lecture (& discussion), with lab assignments. Lectures will be recorded and available for review throughout the semester. • For the second part of the course, students will work on an applied research paper on Operating Systems. • A written project report and optionally, an oral presentation will be required by the date of the final exam.

9. Reports • Every assignment should be submitted in form of a short report. • The final project report is to be submitted as a more complete and longer report.

10. General Report Structure The parts (sections) of a report are: • Title page (name of the institution, department, course name and code/section, name and number of the assignment, name of the persons who have worked in the project, date, etc.) • Initial problem statement • Specification of the problem (description of what is to be solved) • Summary and purpose of the project • Detailed description of the solution and model(s) used in the project. • Description of the implementation

11. General Report Structure (2) 7. Limitations of the above specification and design of the system 8. Discussion of how the system modeled can be improved and extended to include other services. 9. Discussion on the limitations of the method used, including every stage of system development. 10. Comments and Conclusion. 11. List of references (textbooks, journals, WebPages, etc.).

12. Course Content • System Software – Operating Systems • Emphasis on performance metrics • Pre-developed simulation models will be applied for each major topic • Simulation models implemented in C++ and run on Unix. • Assignments are carried out running these simulations and analyzing results • The CS3 server (with Linux) will be used for assignments and project

13. Simple Batch Op Systems • Computer systems in late 50s and early sixties • An operator was needed • User  operator • Main input device - a card reader • 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 back to monitor

14. Types of Software Systems • System software - Operating System, Assemblers, Loaders, Linkers, Compilers, Editors, … • Application software - All User-Oriented Programs. APPLICATION PROGRAMS Users SYSTEM PROGRAMS HARDWARE

15. What is an Operating System? • A large and complex software component for the operation and control of the computer system. • It acts as an intermediary between the a user and the computer system. • Examples: Unix, MS Windows, MacOS, Linux, Sun Solaris, DEC VMS, etc.

16. The Operating System • A provider of services • A huge resource manager

17. System Design Goals • User goals – operating system should be convenient to use, easy to learn, reliable, safe, and fast. • System goals – operating system should be easy to design, implement, and maintain, as well as flexible, reliable, error-free, and efficient.

18. Operating Systems User Interfaces • Graphics GUI (windows oriented) • Command level (shell) At login time, the shell starts computing • System calls Invoked from user programs

19. Memory Layout Simple Batch System

20. Job Control Commands • Problems 1. How does the monitor know about the nature of the job (e.g., Fortran versus Assembly) or which program to execute? 2. How does the monitor distinguish (a) job from job?(b) data from program? • Solution • Introduce control cards

21. Job Control Commands (Cont.) • Special cards that tell the resident monitor which programs to run$JOB$FTN$RUN$DATA$END • Special characters distinguish control cards from data or program cards:$ in column 1// in column 1 and 2709 in column1

22. Control Commands (Cont.) • Parts of resident monitor • Control card interpreter – responsible for reading and carrying out instructions on the cards. • Loader – loads systems programs and applications programs into memory. • Device drivers – know special characteristics and properties for each of the system’s I/O devices. • Problem: Slow Performance – I/O and CPU could not overlap ; card reader very slow. • Solution: Off-line operation – speed up computation by loading jobs into memory from tapes and card reading and line printing done off-line.

23. Spooling • Overlap I/O of one job with computation of another job. While executing one job, the OS • Reads next job from card reader into a storage area on the disk (job queue). • Outputs printout of previous job from disk to printer. • Job pool – data structure that allows the OS to select which job to run next in order to increase CPU utilization.

24. Multiprogramming - Batch Systems Several jobs are kept in main memory at the same time, and the CPU is multiplexed among them.

25. 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.

26. Time-Sharing Systems • 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 is 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” not from a card reader, but rather from the user’s keyboard. • On-line system must be available for users to access data and code.

27. Personal-Computer 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.

28. Migration of Operating-System

29. Multi-processor Systems • Multiprocessor systems with more than one 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

30. Parallel 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 allocates work to slave processors. • More common in extremely large systems

31. Symmetric Multiprocessing Architecture

32. 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. • Hard real-time system. • 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 system • Limited utility in industrial control or robotics • Useful in applications (multimedia, virtual reality) requiring advanced operating-system features.

33. 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

34. Distributed Systems (Cont.) • Network Operating System • provides file sharing • provides communication scheme • runs independently from other computers on the network • Distributed Operating System • less autonomy between computers • gives the impression there is a single operating system controlling the network.

35. Dual-Mode of Operation • Two modes of operation: • User mode – no special privileges • Supervisor mode – when executing OS routines • Protection is maintained by controlling the transition between modes (rather than checking each time an OS routine is executed) • A process when requesting service from the OS, changes mode to supervisor, and provides its own service!

36. System Components • Process Management • Main-Memory Management • File Management • I/O System Management • Secondary-Storage Management • Networking • Protection (address space/errant process) • User Interface (command line&GUI)

37. System Calls • Process Management • Load, execute, end, abort • Create/terminate process • Get or set process attributes • Wait, wait for event, signal event • Allocate and free memory

38. System Calls (cont.) • File Management • Create/delete file • Open/close file • Read,write, reposition pointer • Get/set file attributes • Device Management • Request/release device • Read,write,reposition • Get/set attributes • Mount and unmount device

39. System Calls cont. • Manipulate information and attributes • Get/set file/device/process attributes • Create/delete “environment variables” • Communications • Create/delete channels/links/ports • Send/receive messages • Distributed computing/access • Attach/detach remote devices

40. System Structure – Layered Approach • The operating system is divided into a number of layers (levels), each built on top of lower layers. The bottom layer (layer 0), is the hardware; the highest (layer N) is the user interface. • With modularity, layers are selected such that each uses functions (operations) and services of only lower-level layers.