周期任务模型：Tasks,jobs A task T=1,J2,...,Jn)is a set of related jobs that together perform some operation(如：控制系统) A Job is a unit of work scheduled and executed by the system the unit of concurrency If jobs occur on a regular cycle,the task is periodic A sporadic task is an aperiodic task where the jobs have deadlines once released ·存在“最小到达间隔”！ If jobs have unpredictable release times,a task is termed aperiodic Appear once only?Have average deadlines (soft-RT)? 非周期两种类型：到达模式，软硬实时性(DL) Deadline d 州网 Computation time Period
周期任务模型：Tasks，jobs • A task T= {J1,J2,…,Jn} is a set of related jobs that together perform some operation（如：控制系统） – A Job is a unit of work scheduled and executed by the system • the unit of concurrency – If jobs occur on a regular cycle, the task is periodic – A sporadic task is an aperiodic task where the jobs have deadlines once released • 存在“最小到达间隔”！ – If jobs have unpredictable release times, a task is termed aperiodic • Appear once only? Have average deadlines（soft-RT）？ – 非周期两种类型UnRegistered ：到达模式，软硬实时性（DL）
Arrival Release Completion (invocation)】 周期任务的定时模型 Time Jitter Execution Static task parameters: C,:(urdisturbed)WCET Ti ;={Ci.T.D.O) (relative)deadline (absolute)time offset t O(phase):the interval between a periodic thread creation and its first release time. T 截止时间D可以等于或不等于周期T! 注意：未考虑调度切换开销！ 12/41
12/41 周期任务的定时模型 注意：未考虑调度切换开销！ O(phase): the interval between a periodic thread creation and its first release time。 截止时间D可以等于或不等于周期T！ UnRegistered
Task model Implementation Abstract model task body pl is Interval constant Duration :5.0; Next Time Time; begi Next Time :Clock Interval; gister 100 eex短e+Interval Action; delay until Next Time; =C:T,D, end loop; end P1; task body P2 is Interval constant Duration :7.0; Next TimeTime; begin Next Time :Clock Interval; T2 t2={C2,T,D2,02} 100P Action; delay until Next Time; Next Time :Next Time Interval; end loop; end P2;
Task model UnRegistered
precedence graph,task graphs Independent Periodic jobs (0,7] (2,9] (4,11] (6,13] (8,15] p=2,D=7 。 0 0 Feasible (2,5] (5,8 (8,11] (11,14]d (14,17] Periodic jobs,dependent intervals 0 on immediate predecessor 9-2,p=3,D=3 (0,5] (4,8] (5,20] Cenditional block ---+0 branch (0,6] Jobs with IND complex dependencies (2,10] 2/30R 1/2 Producer-Consumer ·三'：chains、intree(AND/OR)、outtree(branch)
precedence graph，task graphs • 三类：chains、intree(AND/OR)、outtree(branch) UnRegistered
同步粒度synchronization granularity 粒度大小 说明 同步间隔（指令数） 细 单指令流中固有的并行 <20 中等 单独应用中的并行和多任 20~200 务处理 粗 并发进程的多处理 200~2000 非常粗 网络节点上的分布式处理 2000~1M 无约束 无关进程 不适用
同步粒度synchronization granularity UnRegistered