CPU Sch Algorithm-II

CPU Sch Algorithm-II - Operating Systems Structure and...

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Operating Systems Structure and Design CPU scheduling (cont.) multiple-processor scheduling real-time scheduling scheduling algorithm evaluation real-world systems: BSD UNIX, Solaris, Linux, Windows NT/2K, …
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Multiprocessor scheduling CPU scheduling is more complex when multiple CPUs are available symmetric multiprocessing: when all the processors are the same, can attempt to do real load sharing 2 common approaches: 1. separate queues for each processor, processes are entered into the shortest ready queue 1. one ready queue for all the processes, all processors retrieve their next process from the same spot asymmetric multiprocessing:
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Multiprocessor scheduling…. . If several identical processors are available, then load sharing can occur. Possible to provide a separate queue for each processor. Problem : One processor could be idle with an empty queue, while another can be busy Two scheduling approaches: 1. Each processor is self scheduling I.e. each processor examines the common ready queue and selects a process to execute.(access to common data structure) 2. Appointing one processor as scheduler for the other processors-thus, creating a master-slave structure.
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Real-time scheduling hard real time systems requires completion of a critical task within a guaranteed amount of time soft real-time systems requires that critical processes receive priority over less fortunate ones note: delays happen! when event occurs, OS must: handle interrupt save current process load real-time process execute for hard real-time systems, may have to reject processes as
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CPU Sch Algorithm-II - Operating Systems Structure and...

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