Global Real-Time Memory-Centric Scheduling for Multicore Systems
Global Real-Time Memory-Centric Scheduling for Multicore Systems
复制标题
多核系统的以内存为中心的全局实时调度
DOI：
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复制
发表时间：
2016
影响因子：
3.7
通讯作者：
M. Caccamo
中科院分区：
文献类型：
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作者：
Gang Yao;R. Pellizzoni;Stanley Bak;H. Yun;M. Caccamo
随着内核数量的增加，更多的主组件可以同时访问主存。在实时系统中，当计算最坏情况的缓存未命中时间时，这种持续的趋势会导致严重的悲观情绪，因为内存请求可能会与来自系统中其他每个核心的其他请求竞争。因此，以CPU为中心的调度策略不再足以保证可扩展性，而不会为内存密集型任务集引入不可接受的悲观主义。出于这个原因，我们认为需要向实时调度方法转变，这种方法可以防止内存争用造成的时序干扰，同时仍然有效地利用多核平台。在前面，我们已经演示了PREM任务模型的实用性，其中每个作业由一系列阶段组成，其中一些访问内存，另一些只对缓存数据执行计算。在这项工作中，我们提出了第一个全局内存为中心的调度策略，内存密集型任务集的工作可以建模为一系列的内存密集型（内存阶段）和执行密集型（执行阶段）的阶段。所提出的政策是参数化的基础上，允许并发访问主内存而不饱和it.Building从多核响应时间分析的结果，我们引入虚拟内存核心的概念作为一个基本的技术，用于执行基于阶段的响应时间分析内存密集型任务集。最后，我们使用合成任务集生成证明，建议的调度策略和相关的可扩展性约束确实更好地调度内存密集型任务集相比，最先进的多核调度。
As the number of cores increases, more master components can simultaneously access main memory. In real-time systems, this ongoing trend is leading to crippling pessimism when computing the worst-case cache miss time, since a memory request could potentially contend with other requests coming from every other core in the system. CPU-centric scheduling policies, therefore, are no longer sufficient to guarantee schedulability without introducing unacceptable pessimism for memory-intensive task sets. For this reason, we believe a shift is needed towards real-time scheduling approaches that can prevent timing interference from memory contention, while still making efficient use of the multicore platform. Previously, we have demonstrated the practicality of the PREM task model, where each job consists of a sequence of phases, some of which access memory and some of which perform only computation on cached data. In this work, we present the first global memory-centric scheduling policy for memory-intensive task sets whose jobs can be modeled as a sequence of memory-intensive (memory phase) and execution-intensive (execution phase) phases. The proposed policy is parameterizable based on the number of cores which are allowed to concurrently access main memory without saturating it. Building upon results from multicore response-time analysis, we introduce the notion of virtual memory cores as a fundamental technique for performing phase-based response time analysis for memory-intensive task sets. Finally, we use synthetic task set generation to demonstrate that proposed scheduling policy and related schedulability bound do indeed better schedule memory-intensive task sets when compared to state-of-art multicore scheduling.