Operating System

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Operating System by Mind Map: Operating System

1. Objective

1.1. 1. Convenience 2. Efficiency 3. Ability to evolve

2. Role

2.1. Manage the resources of computer which is the movement, storage and processing of data

3. Software

3.1. functions the same way as ordinary computer software

3.2. program or suite of programs executed by the processor

3.3. depend on the processor to allow it to regain control

4. Evolution

4.1. Reasons of evolution:

4.1.1. hardware upgrade

4.1.2. new types of hardware

4.1.3. new services

4.1.4. fixes

4.2. Stages

4.2.1. Serial Processing The earliest computers No operating system Ran from a console with display lights, toggle switches, some form of input devices and a printer access to computer in "series" Problems of Serial Processing Scheduling Setup time

4.2.2. Simple Batch Systems One of early computers but very expensive Monitor no direct access to processor for user job submitted to computer operator that batches them together and put in an input devices programs branches back to the monitor when finished Point of View Monitor Processor Overhead processor time alternates between execution of user program and execution of monitor sacrifices Improves utilization of computer

4.2.3. Multiprogrammed Batch System processor is often idle even with automatic job sequencing I/O devices are slow compared to processor several jobs are kept in main memory at the same time and the CPU is multiplexed among them

4.2.4. Time-Sharing Systems used to handle multiple interactive jobs processor time is shared among multiple user multiple user access system through terminal, with OS interleaving the execution of each user program in a short burst or quantum of computation

5. What is OS?

5.1. A program that controls the execution of application programs

6. Parallel System

6.1. multiprocessor system with more than one CPU in close communication

6.2. Tightly coupled system - processor share memory and a clock(take place through shared memory

6.3. advantages

6.3.1. increase throughput

6.3.2. economical

6.3.3. increased reliability graceful degradation fail-soft system

7. Symmetric Multiprocessing(SMP)

7.1. computer hardware architecture

7.2. OS behaviors that exploits that architecture

7.3. process run in parallel

7.4. transparent to user

7.4.1. share same main memory and I/O facilities

7.4.2. perform the same functions

7.5. takes care of scheduling of threads or processes on individual processor and synchronize it

8. Asymmetric Multiprocessing(SMP)

8.1. assigned a specific task

8.1.1. master processor schedules and allocates work to slave processors

8.1.2. slave processor look to the master processor for instruction

8.2. more common in extremely large systems

9. Distributed Systems

9.1. distribute the computation among several physical processor

9.2. loosely coupled system

9.2.1. each processor has its own local memory

9.2.2. communicates through various communication lines

9.2.3. high-speed buses or telephone lines

9.2.4. advantages resource sharing computation speed up-load sharing reliability communications requires networking infrastructure

10. Real-Time Systems

10.1. particular to the scheduler-very important

10.2. examples

10.2.1. control of laboratory experiments

10.2.2. robotics

10.2.3. air traffic control

10.3. correctness

10.3.1. depends on logical results

10.3.2. time at which the results are produced

10.4. task or process attempt to control or react to events that take place in the outside world

10.5. hard real-time task

10.5.1. one that must meet its deadline

10.5.2. cause unacceptable damage or a fatal error to the system

10.6. soft real-time task

10.6.1. has an associated deadline that is desirable but not mandatory

10.6.2. make sense to schedule and complete the task even if it has passed its deadline

10.7. characteristics

10.7.1. determinism

10.7.2. responsiveness

10.7.3. user control

10.7.4. reliability

10.7.5. fail-soft operation