os hw - OS solutions CS153A Operating System Scheduling 1...

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Sheet1 Page 1 OS solutions CS153A Operating System Scheduling 1) State the trade-offs of each (1 strength and 1 weakness): A) Shortest Job First Ans: +optimal scheduling techniques (assuming we don't consider deadlines. +simple -starvation can occur B) First Come First Served +simple +fair / no starvation - non-optimal - no notion of priorities C) Priority Scheduling + more important jobs can be scheduled ahead of less-important jobs - more complex - starvation can occur D) Round Robin Scheduling - tasks are interrupted - hard to find the right value of the quantum - too short means too high overhead for switching, too long wastes cpu and decreases job response time. + fair + divides up time (long jobs get same time slice as others) E) Multi-Level Feedback + combines round robin and priority to get benefits of both - complex (quanta still need to be identified, now more of them),
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Unformatted text preview: how many levels do you need? 2) Realtime scheduling: A) Define how Rate Monotonic Scheduling works (how is priority set) The task's period is its priority. Each instance of the task has the same priority. Lower values (higher priority) tasks execute first ********************************************************************* Sheet1 Page 2 This one is not on this homework -- but solution is given here for your information: ********************************************************************* B) Define how Deadline Scheduling works (how is priority set) The task's period plus the time at which it enters the system is its priority. Each instance of the task has a different priority (lower each time (b/c higher value)). Lower values (higher priority) tasks execute first...
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  • Fall '09
  • KRINTZ
  • Real-time computing, Scheduling algorithms, Earliest deadline first scheduling

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