Quality Attributes 》 Throughput Availability/Usefulness Response Reliability Security Safety Testability Maintainability Debugability Cost Survivability Image size Available Reliable Safe Confidential Integral Maintainable readiness for usage continuous delivery of no catastrophic no unauthorized no improper alteration ability to undergo service consequences disclosure of of information repairs and evolution information Figure from Burns and Wellings. Dependability Figure 1.1-Dependability 16/87
llxx@ustc.edu.cn 16/87 Quality Attributes • Throughput • Response • Security • Testability • Debugability • Survivability • Availability/Usefulness • Reliability • Safety • Maintainability • Cost • Image size
性能指标 。性能(Performance) -时钟频率、IPS(instructions per second)等 ·但不是好指标：用户关心数码相机产生照片的速度 吞吐率(Throughput) -Tasks per second,相机A每秒处理4幅照片 一吞吐率比延迟可以更好的描述并发性 ·相机B每秒处理8幅照片（存储前一幅照片的同时抓拍一张新照片） 响应时间(response time) 一任务开始到结束的时间 ·相机0.25s完成照片处理 -延迟(Latency) 加速比(Speedup) -如B相对于A的加速比=B的性能/A的性能 Throughput speedup 8/4=2
性能指标 • 性能（Performance） – 时钟频率、IPS（instructions per second）等 • 但不是好指标：用户关心数码相机产生照片的速度 • 吞吐率（Throughput） – Tasks per second, 相机A每秒处理4幅照片 – 吞吐率比延迟可以更好的描述并发性 • 相机B每秒处理8幅照片（存储前一幅照片的同时抓拍一张新照片） • 响应时间(response time) – 任务开始到结束的时间 • 相机0.25s完成照片处理 – 延迟（Latency） • 加速比（Speedup） – 如B相对于A的加速比 = B的性能 / A的性能 • Throughput speedup = 8/4 = 2
“可用性”度量：缓急度函数 USTC 实时任务的松弛度(laxity):决定优先级/实时性等 实线：导弹，晚了，无效或炸错，不如不投。 点线：刷卡消费，连接时间长后，不耐烦或放弃。 短线：股票显示系统，允许一些数据延迟，但可用性下降很快，大的延迟造成损失 Value tardiness FIGURE 3-3 Examples of usefulness functions
• 实时任务的松弛度(laxity)：决定优先级/实时性等 – 实线：导弹，晚了，无效或炸错，不如不投。 – 点线：刷卡消费，连接时间长后，不耐烦或放弃。 – 短线：股票显示系统，允许一些数据延迟，但可用性下降很快，大的延迟造成损失 “可用性”度量：缓急度函数
“成本”度量指标 》 Time-to-prototype:the time needed to build a working version of the system Time-to-market:the time required to develop a system to the point that it can be released and sold to customers Unit cost:the monetary cost of manufacturing each copy of the system,excluding NRE cost 。 NRE cost:The one-time monetary cost of designing the system Non-Recurring Engineering cost ● Flexibility:the ability to change the functionality of the system without incurring heavy NRE cost
“成本”度量指标 • Time-to-prototype: the time needed to build a working version of the system • Time-to-market: the time required to develop a system to the point that it can be released and sold to customers • Unit cost: the monetary cost of manufacturing each copy of the system, excluding NRE cost • NRE cost: The one-time monetary cost of designing the system – Non-Recurring Engineering cost • Flexibility: the ability to change the functionality of the system without incurring heavy NRE cost
Time-to-market:a demanding design metrie ·TTM 一从设计开始到产品可以销售所需的时间 ·Market Window Market Window 一产品投放市场的最佳时间 的 ·平均TTM是8个月 Time (months) ·TTM的推迟将导致产品利润下降
Time-to-market: a demanding design metric • TTM – 从设计开始到产品可以销售所需的时间 • Market Window – 产品投放市场的最佳时间 • 平均TTM是8个月 • TTM的推迟将导致产品利润下降Revenues ($) Time (months) Market Window