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Summary :-Distributed Process Scheduling

Summary :-Distributed Process Scheduling . Prepared By:- Monika Patel. Outline:-. Summary of Chapter 5 A System performance model Static process scheduling Dynamic load sharing and balancing Distributed process implementation Real time scheduling. A system performance model.

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Summary :-Distributed Process Scheduling

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  1. Summary :-Distributed Process Scheduling Prepared By:- Monika Patel.

  2. Outline:- • Summary of Chapter 5 • A System performance model • Static process scheduling • Dynamic load sharing and balancing • Distributed process implementation • Real time scheduling

  3. A system performance model • It gives relationship among algorithm, scheduling and architecture. • Basically three types of model are there:- • Precedence process model:-In this processes are represented by a Directed Acyclic graph (DAG). • This is best applied to the concurrent processes generated by concurrent languages constructs such as fork/join.

  4. Communication process model:-In this model processes are created to co-exist and communicate asynchronously. • It minimizes the interprocessor communication and computation costs of processes on processors. • Disjoint process model:-In this processes run independently and completed in finite time. • Processes are mapped to the processors to maximize the utilization of processes and minimize the turnaround time of the processes.

  5. Static Process Scheduling • The mapping of processes to processor is determined in advance, before the execution process. • Once process started it stays at the processor until completion of the process. • It’s never prompted to move to another processor .

  6. Dynamic load sharing and Balancing • Load balancing can be defined as a technique to distribute work between many computers ,processes or any other resources to get optimal resource utilization. • A process used to route signaling traffic over two or more signaling routes for purposes of traffic equalization or security.

  7. Sender Initiated Algorithm • It is activated by a sender process that wishes to off-load some of its computation. • It also give facility of migration of processes from a heavily loaded sender to a lightly loaded receiver. • Transfer of process form a sender to reciever requires three basic decision. • Transfer policy:-when does the node become the sender? • Selection Policy:-How does the sender choose a process for transfer? • Location Policy:-which node should be the target reciever?

  8. Receiver initiated Algorithm:- • This are the pull models in which receiver can pull a process from others to its site for execution. • They are more stable than the sender initiated algorithm. • At high system load ,process migration are few and a sender can be found easily.

  9. Distributed process implementation • Remote Service:-The message is interpreted as a request for a known service at the remote site • Three different software levels:- • As remote procedure calls at the language level. • As remote commands at the operating system level. • As interpretive messages at the application level.

  10. Remote execution:-The message contain a program to be executed at the remote site. • Some Implementation issues:- • load sharing algorithms. • Location independence. • System heterogeneity. • Protection and security.

  11. Process Migration:-The message represents a process being migrated to the remote site for continuing execution. • Link Direction and message forwarding -Real time example is address changing before moving. • State and context transfer:-It transfers the computation state information and some initial codes.

  12. Real Time Scheduling:- • The systems which insures that certain actions are taken within specified time constraints are called real time systems. • Examples:- • Avionics Computers. • Automobile Control Computers. • Factory automation systems. • Stock trading Systems.

  13. Rate Monotonic:- • It’s easy to implement. • Sorts the tasks by the lengths of their periods. • It also makes very good priority assignments. • Rate monotonic is an optimal priority assignment algorithm.

  14. Deadline Monotonic:-In real time system some tasks need to complete execution a short time after being requested. • Earliest Deadline First:-this is applicable to scheduling aperiodic real time tasks because it only uses the deadlines of the task instantiations. • Real time Synchronization:-A set of tasks that cooperate to achieve a goal will need to share information and resources or other words synchronize with other tasks.

  15. Refrences:- [1] Distributed operating systems & Algorithms,By Randy chow,Theodore johnson.

  16. Thank You.

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