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CSC 7103 20091020

CSC 7103 20091020 - (or you have failed to meet your...

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CSC 7103 10/20/2009 Page 1 of 3 Chapter 5 Process and communication system models Figure 5.5 in textbook List scheduling – no processor remains idle (similar to greedy algorithm). Figure 1 – Sample list scheduling Figure 2 – Sample list scheduling + communication costs
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CSC 7103 10/20/2009 Page 2 of 3 ELS – Extended list scheduling The goal is to schedule the process that can be executed first. Figure 3 – ELS example ETF – earliest task first Figure 4 – ETF example
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CSC 7103 10/20/2009 Page 3 of 3 SKIP Bokari’s Algorithm Understand the concepts around Figure 5.9 in the textbook. Real Time Scheduling Section 5.5 All processes have deadlines. Delay jitter is the variance in the delay of running a task. Earliest deadline first is a very popular algorithm. This is very similar to earliest task first. In aperiodic systems tasks can appear at any time. In periodic systems tasks appear at periodical/ scheduled intervals. In periodic systems, you cannot have more than one instance of the same job running at a time
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Unformatted text preview: (or you have failed to meet your deadline). In real-time systems, the load must stay < 1 or tasks will not complete in time. Rate monotonic Pre-emption is allowed. Without pre-emption, it is possible for task deadlines not to be met because one process might hold the processor causing another job not to complete in time Rate monotonic scheduling relies on the following assumptions: 1. Tasks are periodic and T i is the period for task t i 2. Tasks do not communicate with each other 3. Tasks are scheduled according to priority, and task priorities are fixed (static priority scheduling) (C i , T i ) => (CPU time, period) Then 3 tasks (1,4) (3,9) and (1,2) then priorities from highest to lowest are (1,2), (1,4), (3,9) 1) Given a set of tasks how do we determine if the jobs can be run in a feasible manner? 2) Is this optimal? Is the scheme cannot be scheduled, is there another algorithm that can be used to schedule the tasks?...
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