27 2 Task management University of Electronic Science Technology of China(UESTC) Other problems to be considered Evaluation of a synchronization in real-time multi-core o DS (Direct Synchronization) o PM(Phase Modification) o MPM(Modified Phase Modification) o RG(Release Guard) How to evaluate dS What are the metrics Real-Time Systems Lab LIAO Yong
27 Real-Time Systems Lab LIAO Yong University of Electronic Science & Technology of China (UESTC) 2 Task management Other problems to be considered Evaluation of a synchronization in real-time multi-core o DS (Direct Synchronization) o PM (Phase Modification) o MPM (Modified Phase Modification) o RG (Release Guard) How to evaluate DS ? What are the metrics ?
28 2 Task management University of Electronic Science Technology of China(UESTC) Other problems to be considered Evaluation of a synchronization in real-time multi-core o Performance metrics: 1)Implementation complexity and run-time overhead 2)Average EER (End-to-End Response)times of tasks 3)Estimated worst-case EER times of tasks 0 Evaluation:A simulator is designed to obtain the average EER times 1)4 cores (DM algorithm)+12 tasks(2~8 subtasks) 2)Period is produced randomly in [100,1000] 3)Utilization of a task is produced randomly in [0.001,1] 4)Execution time of a task utilization period Real-Time Systems Lab LIAO Yong
28 Real-Time Systems Lab LIAO Yong University of Electronic Science & Technology of China (UESTC) 2 Task management Other problems to be considered Evaluation of a synchronization in real-time multi-core o Performance metrics: 1) Implementation complexity and run-time overhead 2) Average EER (End-to-End Response) times of tasks 3) Estimated worst-case EER times of tasks o Evaluation: A simulator is designed to obtain the average EER times 1) 4 cores (DM algorithm) + 12 tasks (2~8 subtasks) 2) Period is produced randomly in [100,1000] 3) Utilization of a task is produced randomly in [0.001,1] 4) Execution time of a task = utilization * period
29 2 Task management University of Electronic Science Technology of China(UESTC) Other problems to be considered Elastic scheduling for flexible workload management. WCET (Worst Case Execution Time) o Estimated execution time Actual execution time ea Allowing for precedence and exclusion conditions How to determine the estimated execution time Real-Time Systems Lab LIAO Yong
29 Real-Time Systems Lab LIAO Yong University of Electronic Science & Technology of China (UESTC) 2 Task management Other problems to be considered Elastic scheduling for flexible workload management. WCET (Worst Case Execution Time) o Estimated execution time o Actual execution time Allowing for precedence and exclusion conditions e e a e • How to determine the estimated execution time ?
30 2 Task management University of Electronic Science Technology of China(UESTC) ■ Is real-time scheduling policy enough to ensure the task timeliness (especial for hard real-time tasks) The kernel must respond to external stimuli timely,but how .. Response time is the time the kernel takes to recognize and respond to an external event. Some mechanisms to improve timeliness(Reading...)(p117-p126) o Preemptive scheduling and Preemptive kernel (p118) 0 Shielding time of interruption 0 Data structure心心 (p122,p263,p176) o Memory management o Restrictive waiting time for resource o Priority ceiling Real-Time Systems Lab LIAO Yong
30 Real-Time Systems Lab LIAO Yong University of Electronic Science & Technology of China (UESTC) 2 Task management Is real-time scheduling policy enough to ensure the task timeliness (especial for hard real-time tasks) The kernel must respond to external stimuli timely, but how … ? Response time is the time the kernel takes to recognize and respond to an external event. Some mechanisms to improve timeliness (Reading...) (p117-p126) o Preemptive scheduling and Preemptive kernel (p118) o Shielding time of interruption o Data structure (p122,p263,p176) o Memory management o Restrictive waiting time for resource o Priority ceiling
31 2 Task management University of Electronic Science Technology of China(UESTC) ■ Is real-time scheduling policy enough to ensure the task timeliness (especial for hard real-time tasks) Other mechanisms to improve timeliness o Interruption handling o Floating-point operation Scheduling policy mechanism (Macroscopical idea Operable measurement) Factors that trigger scheduling (p174) >Performance metrics of ERTOS (P145) Multi-processor/Multi-core scheduling (p205) Real-Time Systems Lab LIAO Yong
31 Real-Time Systems Lab LIAO Yong University of Electronic Science & Technology of China (UESTC) 2 Task management Is real-time scheduling policy enough to ensure the task timeliness (especial for hard real-time tasks) Other mechanisms to improve timeliness o Interruption handling o Floating-point operation Scheduling policy & mechanism (Macroscopical idea & Operable measurement) Factors that trigger scheduling (p174) Performance metrics of ERTOS (P145) Multi-processor/Multi-core scheduling (p205)