SYSC-3303-11-Performance

SYSC-3303-11-Performance - SYSC 3303 RealTime Programming...

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SYSC 3303 Real Time Programming Concurrent and Real Time Performance Characteristics
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mporal Requirements Temporal Requirements sure: Ensure: Something happens at/before a specific time Something happens before something else An important job is not delay by something not part of the application A given task set is schedulable 3/11/2009 SYSC 3303 Winter 2009 C. Schramm 2
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mporal equirements Temporal Requirements Kopetz 3/11/2009 SYSC 3303 Winter 2009 C. Schramm 3
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mporal Requirements Temporal Requirements Kopetz 3/11/2009 SYSC 3303 Winter 2009 C. Schramm 4
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mporal Requirements Temporal Requirements Observation of the Controlled Object Delay Jitter : ariability of the Delay Variability of the Delay Output to Real Time Computer Dela y The Actuator Kopetz: Figure 1.5: Computer Delay and Delay Jitter Delay Jitter: Sensitivity parameter for the quality of the control loop Uncertainty about the instant the RT entity was observed (i.e. temperature), leading to an error value of the measured variable. elay jitter should be small fraction of delay 3/11/2009 SYSC 3303 Winter 2009 C. Schramm 5 Delay jitter should be small fraction of delay
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heduling: Definition Scheduling: Definition System : {Processors, Resources} Workload : { jobs or task} Task Scheduler : Algorithm for ordering the use of system by the workload. means of predicting the worst se ehaviour f the A means of predicting the worst case behaviour of the system when the scheduling algorithm is applied. Real Time temporal requirements are met if the k hdl (l i th ) b h t task scheduler (algorithm) can be shown to handle the worst case execution time (WCET) of the workload on the system 3/11/2009 SYSC 3303 Winter 2009 C. Schramm 6
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sk Scheduling Models Task Scheduling Models 1. Timing: Rates and Responses Periodic Tasks Periodic Polling or Periodic Event Driven (Interrupts) ate Requirement: Rate Requirement: Task must provide service at a particular rate N Events per second eriodic or Sporadic Tasks A periodic or Sporadic Tasks Event driven Response Requirement: hen event X occurs the task must respond to it within a given When event X occurs, the task must respond to it within a given amount of time 2. Interaction Complexity: … 3/11/2009 SYSC 3303 Winter 2009 C. Schramm 8
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sk Scheduling Models Task Scheduling Models 1. Timing: Periodic and A periodic/Sporadic Tasks 2. Interaction Complexity: S Tasks : Simple task with no synchronization point; tt d ti til ti t i once started, continues until termination Cannot be blocked WCET is a local issue : Not directly related to progress of th tk ( b ll t d id d t l) other tasks (can be calculated independently) C : Complex task contains blocking synchronization statement(s) WCET is a global issue : Directly related to progress of other tasks (cannot be calculated independently) Techniques: Precedence Graphs and Task Graphs 3/11/2009 SYSC 3303 Winter 2009 C. Schramm 9
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sk Scheduling Definitions Task Scheduling Definitions Release Time :
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This note was uploaded on 07/16/2009 for the course SYSC 3303 taught by Professor Shramp during the Spring '09 term at Carleton CA.

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SYSC-3303-11-Performance - SYSC 3303 RealTime Programming...

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