cs6235-4A-feedback-FG

cs6235-4A-feedback-FG - CS 4220/6235 Feedback Scheduler for...

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CS 4220/6235 Feedback Scheduler for Real-Rate 1 1 CS4220 Embedded Systems CS6235 Real CS6235 Real-Time Systems Time Systems 4A: Feedback Scheduling Instructor: Calton Pu [email protected] TAs: Qinyi Wu ([email protected]) Peter Budny ([email protected]) 2 Network Client Decoder Server Filter Media Server Motivation l Real-rate applications Real-world performance demands l Automated rate matching fine-grain adjustment of allocation dynamic response to variable rates low programming complexity
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CS 4220/6235 Feedback Scheduler for Real-Rate 2 3 Priority Schedulers l Give CPU to highest priority task l Scheduling policy Assigns priorities to tasks l Scheduling mechanism Sort runnable task queue according to priorities Run the task at the head of the queue l Example of problems Priority inversion 4 Proportional Scheduler l Give tasks a proportional share of CPU l Scheduling policy Assign proportions to tasks l Scheduling mechanism Round-robin queue Time slice allocated according to the proportion l Example of problems Need to cycle through queue fast
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CS 4220/6235 Feedback Scheduler for Real-Rate 3 5 Current Schedulers l Priority-based schedulers all-or-nothing or equal share: coarse grained l unless aided by the application programmer: high complexity l Proportional-share schedulers require program to specify resource needs: high complexity hard to know for variable rate apps : lack dynamic response 6 Unix Scheduler Problem Process 1 10ms/char Process 2 100ms/char Process 3 1ms/char
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CS 4220/6235 Feedback Scheduler for Real-Rate 4 7 Feedback Approach Dynamic
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This note was uploaded on 10/10/2010 for the course CS 6235 taught by Professor Staff during the Fall '08 term at Georgia Tech.

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cs6235-4A-feedback-FG - CS 4220/6235 Feedback Scheduler for...

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