Multi processors notes

symmetric multiprocessors
In which each processor runs an identical copy of the operating system
- all processors are peers
- no master slave relation exists between processors

asymmetric multiprocessors( master slave model)

- In which each processor is assigned a specific task
- this scheme defines a master slave relationship

Real time Systems
===== ========
- It is special purpose operating system
- It is used when rigid time requirements have been placed on the operation of a processor or the flow of data
- real time system has well defined, fixed time constraints, processing must be done within the defined constraints else the system fails

they can be classified as Soft and Hard
-----------------------------------------
HARD
=====
  • Guarantees that critical tasks be completed on time
  • delay in system must be bounded
  • secondary storage of any kind is minimal(limited) or missing
  • most advanced feature of OS will not be supported(ex: virtual memory)
  • None of the existing General purpose operating system support for hard real time
SOFT
=====
  • critical real-time process or task gets priority over other tasks and retains priority until it completes
  • ex: multi media processing

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