| 摘要: |
| 面向通用计算机系统的指令预取技术无法满足实时系统的应用需求，其中一个重要原因是：无效预取引起的指令Cache内容污染使得实时任务WCET评估值不够精确，导致系统可调度性下降，严重影响系统效率.以简化实时任务WCET分析、降低任务WCET评估值为目标，提出一种基于程序基本块的指令预取方法.该方法以基本块为粒度执行指令预取，避免了传统指令预取技术引入的无效预取；通过简化最坏情况下的指令访问命中/缺失情况判定，简化任务WCET分析过程并优化WCET评估值.实时基准测试程序评估结果表明：与常规无预取方法相比，该预取方法可使实时任务WCET评估值降低约20%，平均执行情况下的指令Cache访问性能提升约10%. |
| 关键词: 实时系统 最坏情况执行时间 高速缓存性能 指令预取 基本块 |
| DOI：10.13328/j.cnki.jos.004859 |
| 分类号: |
| 基金项目:国家高技术研究发展计划（863）（2013AA011701） |
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| Basic-Block Based Instruction Prefetching Technology for Real-Time System |
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WANG En-Dong, NI Fan, CHEN Ji-Cheng, WANG Hong-Wei, TANG Shi-Bin
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State Key Laboratory of High-end Server & Storage Technology (Inspur(Beijing) Electronic Information Industry Co., Ltd), Beijing 100085, China
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| Abstract: |
| Instruction prefetching technologies proposed for general purpose computer systems cannot meet the requirements of real- time systems. One of the most important issues is that cache content pollution caused by useless prefetching loses real-time tasks' WCET estimates. And a loose on WCET analysis degrades the schedulability of the system and in turn brings down its efficiency. A basic-block based instruction prefetching method is proposed in this paper. The method performs instruction prefetching at the basic block level, avoids useless prefetching, simplifies the instruction hit/miss classifications in the worst-case execution, and reduces the WCET estimates of real-time tasks. Real-time benchmark tests show that, the method can reduce real-time tasks' WCET estimates by 20% and also improve instruction cache access performance by 10% on average. |
| Key words: real-time system WCET cache performance instruction prefetching basic block |
