CSR: Small: Collaborative Research: Exploring Portable Data Placement on Massively Parallel Platforms with Heterogeneous Memory Architectures

异构计算在许多计算领域变得至关重要，包括星系的模拟、社会网络的分析、股票交易的建模等等。异构存储系统的编程是一个巨大的挑战，由于编程的复杂性和硬件的快速发展，它成为异构硬件和应用程序之间的主要障碍。这个项目旨在解决这个障碍，并期望极大地减轻程序员处理底层内存系统异构性的负担。这项研究的成果还将使未来异构系统上许多应用程序的计算效率不断提高，这是科学、健康、安全和人类其他方面持续进步的关键条件。为了解决异构内存系统上的编程挑战，该项目研究了一个软件框架，该框架由硬件规范语言、一组新颖的编译器和运行时技术以及高级内存性能建模组成。目标是开发一个系统的解决方案来自动放置给定的复杂异构内存系统中的数据，特别是在大规模并行平台上。在该框架下，编程人员不必根据不同的存储系统来编写程序，同时，复杂的存储系统可以完全转化为高计算效率。该框架将程序转换为自定义的（根据数据在内存中的位置、何时以及如何迁移等），并在运行时将其转换为底层异构内存系统，从而获得接近最佳的内存使用。

Heterogeneous computing is becoming crucial for many computational fields, including simulations of the galaxy, analysis of social networks, modeling of stock transactions, and so on. Programming heterogeneous memory systems is a grand challenge, and creates a major obstacle between heterogeneous hardware and applications because of the programming complexity and fast hardware evolution. This project aims to address this obstacle, and is expected to significantly relieve programmers from handling the underlying memory system heterogeneity. The outcome from this research will also enable continuous enhancement of the computing efficiency of a number of applications on future heterogeneous systems, which is a critical condition for sustained advancement of science, health, security and other aspects of humanity.To address the programming challenges on heterogeneous memory systems, the project investigates a software framework, consisting of a hardware specification language, a set of novel compiler and runtime techniques, and advanced memory performance modeling. The goal is to develop a systematic solution to automatically place data given a complex heterogeneous memory system, especially on massively parallel platforms. With the proposed framework, programmers are relieved from tailoring their programs to different memory systems, and at the same time, the sophisticated memory systems can get fully translated into high computing efficiency. The framework transforms the programs such that they are customized - in terms of where data are placed in memory, when and how to migrate, etc. - to the underlying heterogeneous memory system at runtime and attain a near optimal memory usage.