2 University of Electronic Science Technology of China(UESTC) Chapter 4 Task Management Real-Time Systems Lab LIAO Yong
2 Real-Time Systems Lab LIAO Yong University of Electronic Science & Technology of China (UESTC) Chapter 4 Task Management
3 1 Overview University of Electronic Science Technology of China(UESTC) Task management Scheduling Policy Synchronization,Communication,Mutex Coordinate mechanism Memory management Inventory management mechanism Interruption Time management Event dealing mechanisms: Event-triggered mechanism Time-triggered mechanism Real-Time Systems Lab LIAO Yong
3 Real-Time Systems Lab LIAO Yong University of Electronic Science & Technology of China (UESTC) 1 Overview Task management Synchronization,Communication,Mutex Memory management Interruption & Time management Event dealing mechanisms: Event-triggered mechanism Time-triggered mechanism Coordinate mechanism Inventory management mechanism Scheduling Policy
4 2 Task management University of Electronic Science Technology of China(UESTC) _What does the kernel do Scheduling What does the kernel scheduling Tasks >What are tasks Real-Time Systems(RTS)? >Characteristics of tasks o Concurrence (Simultaneousness) Scheduler o Dynamic o Asynchrony Independence (Synchrony dependence) 0… Real-Time Systems Lab LIAO Yong
4 Real-Time Systems Lab LIAO Yong University of Electronic Science & Technology of China (UESTC) 2 Task management What does the kernel do ? Scheduling What does the kernel scheduling ? Tasks What are tasks & Real-Time Systems (RTS)? Characteristics of tasks o Concurrence (Simultaneousness) o Dynamic o Asynchrony & Independence (Synchrony & dependence) o …… Scheduler
5 2 Task management University of Electronic Science Technology of China(UESTC) >Classification of tasks o Periodic tasks o Sporadic tasks o Aperiodic tasks Critical tasks Non-critical tasks Hard real-time tasks √Soft real--time tasks Real-Time Systems Lab LIAO Yong
5 Real-Time Systems Lab LIAO Yong University of Electronic Science & Technology of China (UESTC) 2 Task management Classification of tasks o Periodic tasks o Sporadic tasks o Aperiodic tasks Critical tasks Non-critical tasks Hard real-time tasks Soft real-time tasks
6 2 Task management University of Electronic Science Technology of China(UESTC) How to schedule tasks on processor to ensure that their deadlines are met >Tasks and their special requirements o Task: T（=1,2,n) o Task number: n o Period: P o Executing time: e; o Relative deadline: D o Absolute deadline: d What's the difference between task and process? o Release time: ri Time related parameters o Phasing: 工 Real-Time Systems Lab LIAO Yong
6 Real-Time Systems Lab LIAO Yong University of Electronic Science & Technology of China (UESTC) 2 Task management How to schedule tasks on processor to ensure that their deadlines are met ? Tasks and their special requirements ? o Task: Ti ( i=1,2,…,n ) o Task number: n o Period: Pi o Executing time: ei o Relative deadline: Di o Absolute deadline: di o Release time: ri o Phasing: Ii What's the difference between task and process? Time related parameters