Improved cache related pre-emption delay aware response time analysis for fixed priority pre-emptive systems
Improved cache related pre-emption delay aware response time analysis for fixed priority pre-emptive systems
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DOI：
10.1007/s11241-012-9152-2
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发表时间：
2011-11
影响因子：
1.3
通讯作者：
S. Altmeyer;Robert I. Davis;Claire Maiza
中科院分区：
文献类型：
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作者：
S. Altmeyer;Robert I. Davis;Claire Maiza
如果不使用高速缓存，现代嵌入式微处理器中处理器和存储器速度之间的差距越来越大，将导致存储器访问时间成为不可接受的瓶颈。在这样的系统中，高速缓存相关的抢占延迟可以是任务执行时间的显著比例。为了得到抢占式调度系统中任务响应时间的严格界，有必要通过使用一个合适的抢占代价模型，将最坏情况执行时间分析和可调度性分析结合起来，本文介绍了一种新的抢占代价界方法，称为ECB-Union方法。欧洲中央银行-联盟办法补充了现有的欧洲中央银行-联盟办法。我们通过引入多集变量来改进这两种方法，从而减少分析中的悲观情绪。此外，我们联合收割机这些多集方法结合成一个简单的复合方法，占主导地位。这些方法绑定抢占成本集成到响应时间分析固定优先级抢占调度系统。此外，我们将这种分析扩展到任务可以访问互斥资源的系统，在此过程中解决现有模型的抢占延迟遗漏。案例研究和实证评估证明了ECB联盟，多集和组合方法的有效性，广泛的不同的缓存配置，包括缓存利用率，缓存集大小，重用和块重新加载时间。
Without the use of caches the increasing gap between processor and memory speeds in modern embedded microprocessors would have resulted in memory access times becoming an unacceptable bottleneck. In such systems, cache related pre-emption delays can be a significant proportion of task execution times. To obtain tight bounds on the response times of tasks in pre-emptively scheduled systems, it is necessary to integrate worst-case execution time analysis and schedulability analysis via the use of an appropriate model of pre-emption costs.In this paper, we introduce a new method of bounding pre-emption costs, called the ECB-Union approach. The ECB-Union approach complements an existing UCB-Union approach. We improve upon both of these approaches via the introduction of Multiset variants which reduce the amount of pessimism in the analysis. Further, we combine these Multiset approaches into a simple composite approach that dominates both. These approaches to bounding pre-emption costs are integrated into response time analysis for fixed priority pre-emptively scheduled systems. Further, we extend this analysis to systems where tasks can access resources in mutual exclusion, in the process resolving omissions in existing models of pre-emption delays. A case study and empirical evaluation demonstrate the effectiveness of the ECB-Union, Multiset and combined approaches for a wide range of different cache configurations including cache utilization, cache set size, reuse, and block reload times.