The adoption of multi-cores for mixed-criticality systems has fueled research on techniques for providing scheduling isolation guarantees to applications of different criticalities. These are especially hard to provide in the presence of contention in shared resources of the system, such as buses and DRAMs. The state-of-the-art Single-Core Equivalence (SCE) framework improves timing isolation by enforcing periodic memory access budgets per core, which allows computing safe stall delays for the cores as input to the schedulability analysis. In this work, we extend the theoretical toolkit for this state-of-the-art framework by considering EDF and server-based scheduling, instead of partitioned fixed-priority scheduling which SCE has assumed so far. A second extension to the theory of SCE consists in additionally allowing memory access budgets to be uneven and defined on a per-server basis, rather than just on a per-core basis, which is what was supported until now. This added flexibility allows better memory bandwidth efficiency, especially when servers with dissimilar memory access requirements co-exist on a given core, and this in turn improves schedulability. Finally, we also formulate an Integer-Linear Programming Model (ILP) guaranteed to find a feasible mapping of a given set of servers to processors, including their execution time and memory access budgets, if such a mapping exists. Our experiments with synthetic task sets confirm that considerable improvement in schedulability can result from the use of per-server memory access budgets under the SCE framework.

中文翻译：

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用于在多核平台上调度 IMA 应用程序的不均匀内存调节

在混合临界系统中采用多核推动了对为不同临界应用提供调度隔离保证的技术的研究。在系统的共享资源（例如总线和 DRAM）中存在争用时，这些尤其难以提供。最先进的单核等效 (SCE) 框架通过强制执行每个内核的定期内存访问预算来改善时序隔离，这允许计算内核的安全停顿延迟作为可调度性分析的输入。在这项工作中，我们通过考虑 EDF 和基于服务器的调度来扩展这个最先进框架的理论工具包，而不是 SCE 迄今为止假设的分区固定优先级调度。SCE 理论的第二个扩展包括另外允许内存访问预算不均匀，并在每个服务器的基础上定义，而不仅仅是在每个核心的基础上，这是迄今为止所支持的。这种增加的灵活性允许更好的内存带宽效率，特别是当具有不同内存访问要求的服务器在给定核心上共存时，这反过来又提高了可调度性。最后，我们还制定了一个整数线性编程模型 (ILP)，保证找到一组给定的服务器到处理器的可行映射，包括它们的执行时间和内存访问预算，如果这样的映射存在的话。我们对合成任务集的实验证实，在 SCE 框架下使用每服务器内存访问预算可以显着提高可调度性。