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- 1. Fred Kuhns ( ) CS523S: Operating Systems CS523 Operating Systems Fred Kuhns Applied Research Laboratory Computer Science Washington University
- 2. Fred Kuhns ( ) CS523S: Operating CS523 - Operating Systems • Instructor: Fred Kuhns • Phone: 935-6598 • Email: fredk@cs.wustl.edu • Office Hours: Tu/Th: 4:00 - 5:00PM • Location: TBD • Class times: Tu/Th: 2:30 - 4:00PM
- 3. Fred Kuhns ( ) CS523S: Operating Course Materials • Textbook: Real-Time Systems, Jane W. S. Liu • Selected papers from the literature, • Class handouts and presentation material, • Class web page, • OS man pages and web accessible documentation, • UNIX account.
- 4. Fred Kuhns ( ) CS523S: Operating Programming Projects • 3 projects plus a final project • Final project: team/individual class presentations address a system issue covered in class. May build on class projects. Report or implementation. • Project focus: Correct, predictable behavior (of implementation) Performance (efficient execution) Completeness of design (address all issues) "readability" of code (can I understand it)
- 5. Fred Kuhns ( ) CS523S: Operating Exams, Homework and Grading • Weekly: Homework assignment or Quiz • Final Exam (no mid-term): Comprehensive • Relative weights: 25% Final exam 20% Quizzes 10% Homework 30% Programming projects (10% per project) 15% Final Project
- 6. Fred Kuhns ( ) CS523S: Operating Course Overview Overview of OS design issues o Review of general purpose OS services o Intro to Advanced OS Topics: • Real-Time, Database, Distributed and Multi-processor Detailed analysis of conventional OS internals: o Focus on UNIX - Linux, BSD, SVR4 and Mach o Single/Multi-processor o Resource management Focus on Real-Time: design and implementation o Performance and predictability issues o Resource scheduling and managing concurrency
- 7. Fred Kuhns ( ) CS523S: Operating Introduction • Functions of an Operating System Resource management User environment • Design Approaches Layered, Kernel and Virtual • Types of Advanced Operating Systems Distributed, Multiprocessor, Database and Real-time • Overview of UNIX (why do we care)
- 8. Fred Kuhns ( ) CS523S: Operating Functions of an OS • Resource Management Time management - temporal properties CPU and disk transfer scheduling Space management main and secondary storage allocation Synchronization and deadlock handling c Accounting and status information s
- 9. Fred Kuhns ( ) CS523S: Operating Functions of an OS (cont) • User Environment - OS layer transforms bare hardware machine into higher level abstractions Execution environment - process management, file manipulation, interrupt handling, I/O operations, language. Error detection and handling Protection and security Fault tolerance and failure recovery
- 10. Fred Kuhns ( ) CS523S: Operating Design Approaches • Deal with complexities of modern systems • Separation of Policies and Mechanisms Policies - What should be done Mechanisms - How it should be done Levin, R., E. Cohen, W. Corwin, F. Pollack and W. Wulf, "Policy/Mechanism Separation in HYDRA," Proceedings of the 5th Symposium on Principles of Operating Systems, 1975, pp. 132-140. • Three common approaches: Layered Approach Kernel Approach Virtual Machine Approach
- 11. Fred Kuhns ( ) CS523S: Operating Layered Approach Level Name Objects Example 13 Shell User programming env. Bash statements 12 User process User process Quit,kill,suspend,resume 11 Directories Directories Create,destroy,attach,list 10 Devices External: printer,display Create,open,close 9 File system Files Create,open,close 8 Communications Pipes Crreate,open,close 7 Virtual memory Segments,pages Read,write,fetch 6 Local secondary store Blocks,channel Read,write,fetch 5 Primitive process Process,semaphore Suspend,resume,wait 4 Interrupts Interrupt-handlers Invoke,mask,retry 3 Procedures Procedure,stack,display Mark stack,call,return 2 Instruction set Evaluation stack Load,store,add 1 Electronic circuit Registers,gates,buses Clear,transfer,activate Simplifies design, implementation and testing Modular by dividing OS into functional layers. HWresourceenvironment
- 12. Fred Kuhns ( ) CS523S: Operating Kernel Based Approach Kernel contains a collection of primitives which are used to build the OS OS implements policy Kernel implements mechanisms Hardware kernel Operating system
- 13. Fred Kuhns ( ) CS523S: Operating Virtual Machine Approach Virtual software layer over hardware Illusion of multiple instances of hardware Supports multiple instances of OSs Hardware Virtual machine software VM1 VM2 VM3 VM4
- 14. Fred Kuhns ( ) CS523S: Operating • Layered: Dijkstra, E. W., "The Structure of THE Multiprogramming System", Communications of the ACM, May 1968, pp. 341-346. • Layered (Ring): Organick, E., The Multics System, MIT Press, Cambridge, MA. 1972. • Kernel Brinch Hansen, P., "The Nucleus of a Multiprogramming System", Communications of the ACM, Apr. 1970, pp. 238-241. Wulf, W., E. Cohen, W. Corwin, A. Jones, R. Levin, C. Pierson, and F. Pollack, "HYDRA: The Kernel of a Multiprocessor Operating System", Communications of the ACM, June 1974, pp. 337-345. • Virtual Seawright, L., and R. MacKinnon, "VM/370 - A Study of Multiplicity and Usefulness", IBM Systems Journal, 1979, pp. 4-17.
- 15. Fred Kuhns ( ) CS523S: Operating Types of Advanced OSs Distributed Operating Systems Multiprocessor Operating Systems Database Operating Systems Real-time Operating Systems
- 16. Fred Kuhns ( ) CS523S: Operating Distributed Operating Systems • Controls and manages resources for a network of autonomous computers manage both hardware and software resources behaves as a single monolithic system. • User not aware of program or resource location • Design issues same as traditional systems • Practical issues: lack of shared memory lack of global clock unpredictable communication delays.
- 17. Fred Kuhns ( ) CS523S: Operating Multiprocessor Operating Systems • Consists of a set of processors that share a set of physical memory blocks share a common clock "share" over an interconnection network. • Control and manage resources hardware and software resources viewed as a uniprocessor system. • Design issues same as traditional system. • Practical issues: increased complexity of synchronization, scheduling, memory management, protection and security.
- 18. Fred Kuhns ( ) CS523S: Operating Database Operating Systems • Database systems place increased demands on an operating system to efficiently support: concept of a transactions manage large volumes of data concurrency control system failure control
- 19. Fred Kuhns ( ) CS523S: Operating Real-time Operating Systems • Place application specific special requirements on an operating system. • Policies and mechanisms are geared to ensuring jobs meet their deadlines. • Problem is one of resource scheduling and overall system utilization.
- 20. Fred Kuhns ( ) CS523S: Operating Why UNIX • Historical significance • Advanced features developed for or ported to UNIX • Availability of source code and research papers • Importance to present and future research activities at WashU • Highlights key design and architectural issues
- 21. Fred Kuhns ( ) CS523S: Operating Traditional UNIX kernel • Bloated kernel • Inflexible: supported single type of file system, process scheduling executable file format file system virtual memory loader block dev char dev kernel
- 22. Fred Kuhns ( ) CS523S: Operating Modern UNIX • Separation of policy and mechanism • modular design and implementation (layered) AcrobatDocum ent
- 23. Fred Kuhns ( ) CS523S: Operating References • Original UNIX implementation: D. M. Ritchie, and K. Thompson, “The UNIX Time-Sharing System”, Communications of the ACM, Vol. 17, No. 7, Jul. 1974, pp. 365-375.