VAMPIR – Virtualized Non-Functional Memory Properties for Data-Pipeline Scheduling

现代硬件的最新进展可以被认为是硬件/软件协同设计的一个拐点。特别是，内存和存储已经发生了前所未有的变化：新的技术模糊了传统的内存层次结构的心理图景；非易失性RAM肯定是质疑这一范式的最突出的例子。然而，超大型缓存、高带宽内存(HBM)、非统一内存访问(NUMA)，甚至远程内存设计和速度极快的固态硬盘都将NVRAM加入到各种可用的内存/存储技术组合中。因此，脑海中的画面现在更像是一池记忆技术，每一种技术都位于多维设计空间中。在我们设想的Vampir项目中，我们追求的研究假设是，只有充分和创新的OS/App联合设计才能完全拥抱和利用异质存储器的个体属性。一方面，我们看到了对操作系统(OS)的明确需求，它不仅提供对内存的访问，而且提供具有虚拟地址空间以外的功能的虚拟内存层。例如，操作系统应该透明地为内存分配提供压缩、加密或提高容错能力，最高可达n模冗余。另一方面，我们设想未来的应用程序将以更具描述性的方式与操作系统进行通信，并协商应用程序所需的各个属性。在这方面，我们将重点放在数据密集型应用程序类上，它部署的单个数据流包括(A)具有沿管道的非阻塞操作符的依赖数据管道网络和(B)将阻塞操作符作为管道之间的连接点。在SPP 2377的背景下，我们的Vampir提案的目标恰恰是优化基于数据管道的数据密集型应用程序的执行与中断内存技术上的虚拟非功能内存属性之间的相互作用。我们的核心思想是将(A)操作系统针对非功能要求提供内存分配的能力--就能力和时间属性而言--与(B)数据流水线处理的机会与预定义的流水线执行时间表和相关的内存要求相结合。我们设想以双向的方式调查这一组合，以允许协商内存要求和资源调配，从而推动操作系统/应用程序联合设计的极限。

Recent advances in modern hardware can be considered an inflection point for HW/SW co-design. Especially memory and storage has seen an unprecedented change: Novel techniques have blurred the traditional mental picture of the memory hierarchy; non-volatile RAM is certainly the most prominent example to question this paradigm. However, very large caches, High-Bandwidth-Memory (HBM), Non-Uniform Memory Access (NUMA), or even remote-memory designs and extremely fast SSDs join NVRAM in the heterogeneous portfolio of available memory/storage techniques. Consequently, the mental picture is now rather that of a pool of memory techniques, each positioned in a multidimensional design space. Unfortunately, this large degree of freedom makes it difficult for applications to efficiently and effectively use these memories.Within our envisioned VAMPIR project, we pursue the research hypothesis that only an adequate and innovative OS/App co-design can fully embrace and exploit the individual properties of heterogeneous memories. On the one hand, we see a clear demand for an operating system (OS) to offer more than just access to memory, but to provide a virtualized memory layer with features beyond virtual address spaces. For example, the OS should transparently provide compression, encryption, or increased fault-tolerance up to n-modular redundancy for memory allocations. On the other hand, we envision future applications to communicate much more descriptively with the OS and negotiate individual properties required by the application. For this aspect, we focus on the class of data-intensive applications, which deploy individual data streams consisting of (a) a network of dependent data pipelines with non-blocking operators along a pipeline and (b) blocking operators as connection points between pipelines. Within the context of the SPP 2377, our VAMPIR proposal targets exactly the interplay of optimizing the execution of data-intensive applications based on data pipelines with respect to virtualized non-functional memory properties on disruptive memory technologies. Our core idea is to combine (a) the capability of an OS providing memory allocations with respect to non-functional requirements – in terms of capabilities as well as temporal properties – with (b) the opportunity of data-pipeline processing with a pre-defined schedule of pipeline executions and dependent memory requirements. We envision to investigate the combination in a bi-directional manner to allow negotiation of memory requirements and provisioning, thus pushing the envelope in OS/App co-design.