A. Frank - P. Weisberg Operating Systems Operating System Structures
2 A. Frank - P. Weisberg Operating System Structures • Operating System Services • Common System Components • System Calls and APIs • System Programs • System Design and Implementation • System Pragmatics
3 A. Frank - P. Weisberg A View of Operating System Services
4 A. Frank - P. Weisberg OS Services (user-oriented ( • Program execution – OS capability to load a program into memory, run it, end execution, either normally or abnormally (indicating error). • I/O operations – since user programs cannot execute I/O operations directly, the OS must provide some means to perform I/O, which may involve a file or I/O device. • File systems – program capability to read, write, create, and delete files and directories. • Communication – Processes may exchange information, on the same computer or between computers over a network – Implemented via shared memory or message passing. • Error detection – ensure correct computing by detecting errors in the CPU and memory hardware, in I/O devices, or in user programs.
5 A. Frank - P. Weisberg Communication Models • Communication may take place using either (a) message passing or (b) shared memory.
6 A. Frank - P. Weisberg OS Services (system-oriented ( • Resource allocation – When multiple users or multiple jobs running concurrently, resources must be allocated to each of them. • Accounting – To keep track of which users use how much and what kinds of computer resources • Protection and security – The owners of information stored in a multi-user or networked computer system may want to control use of that information, while concurrent processes should not interfere with each other – If a system is to be protected and secure, precautions must be instituted throughout it; a chain is only as strong as its weakest link.
7 A. Frank - P. Weisberg Common System Components • Process Management • Main Memory Management • Storage/File System Management • I/O System Management • Mass-Storage Management • Networking • Command Interpreter • Protection and Security
8 A. Frank - P. Weisberg Process Management (1 ( • A process is a program in execution. It is a unit of work within the system. • Program is a passive entity, process is an active entity. • The operating system is responsible for the following activities in connection with process management: – Creating and deleting both user and system processes. – Suspending and resuming processes. – Providing mechanisms for process synchronization. – Providing mechanisms for process communication. – Providing mechanisms for deadlock handling.
9 A. Frank - P. Weisberg Process Management (2 ( • A Process needs resources to accomplish its task: – CPU, memory, I/O devices, files – Initialization data • Process termination requires reclaim of any reusable resources.
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- Summer '18
- P. Weisberg, A. Frank