RTOS view of Reaction event response to event -response interval process made interrupt available processing real-time dispatch latency process execution conflicts dispatch Arrival Release Completion (invocation) ∩Deadline d Time Jitter Execution Computation time Period Response Time
RTOS view of Reaction UnRegistered
Constraints on Tasks (OS view Arrival Release Completion ·Timing(定时)constraints (invocation)】 -Release time Relative to arriving time Time -Deadline Jitter Execution ·Absolute deadline Response Time o Precedence(优先)constraints,偏序 Temporal order:Temporal dependence ·temporal distance:“完成时间"之差 - Causal order:Causal dependence Happen-before(Lamport) Resource constraints Data dependence ·Mutual exclusion Resource access protocols
Constraints on Tasks（OS view） • Timing(定时) constraints – Release time • Relative to arriving time – Deadline • Absolute deadline • Precedence(优先) constraints，偏序 – Temporal order：Temporal dependence • temporal distance： “完成时间”之差 – Causal order：Causal dependence • Happen-before(Lamport) • Resource constraints – Data dependence • Mutual exclusion • Resource access protocols UnRegistered
非周期任务的定时模型(tos) Arrival Release Completion (invocation) Time Si e f d Release Time Jitter Execution 当T=O和Uter=0时：Arrival=Release=Start Response Time a:到达时刻arrival/request relative deadline D, s:开始调度时刻stat e; 调度结束时刻/release 天完成时刻 a d 下：切换时间 absolute deadline C.执行时间Workload response time Ri (di=ai+Ri) R:响应时间 截止期：绝对d(动态，时刻)，相对D(静态，时间)，开始时限 延迟Lateness:f-d 8/41
8/41 非周期任务的定时模型(rtos) a：到达时刻arrival/request s: 开始调度时刻start e: 调度结束时刻/release f： 完成时刻 T: 切换时间 C: 执行时间/Workload R：响应时间 截止期：绝对d（动态，时刻），相对D（静态，时间），开始时限 延迟Lateness：f – d 当T=0 和 Jitter=0 时：Arrival = Release = Start UnRegistered
松弛时间slack(裕度laxity)、WCE D Si R siacki=di-f 延迟Lateness:=f'-d AET (Actual Execution Time) siack 2 {1) Task Task ■■■■■■■■■■■■ 0 Deadline=Period BCET (Best Case Execution Time)WCET (Worst Case Execution Time)
松弛时间slack（裕度laxity）、WCET 延迟Lateness=f ‘– d f' L UnRegistered
Arrival Release Completion (invocation) Types of Jitter Time Finishing-time Jitter Release Time Jitter Execution ti f Start-time Jitter T Sil Si.2 Si.3 Completion-time Jitter (I/O Jitter) Si1 fil S1,2 fi2 Si.3
Types of Jitter UnRegistered