Collaborative Research: Programming Models, Compiles, and Runtimes for High-end Computing on Manycore Processors

由于众核技术的出现，高端计算（HEC）领域正处于一个主要的十字路口--在单个芯片上集成数十个和数百个处理器（核心），在2015-2020年的时间框架内，在Exascale系统中每个芯片将达到1000个核心。与前几代硬件发展不同，硬件路线图的这种转变将对未来的HEC软件产生深远的影响。首先，程序员将面临在单个系统中表达和管理数百万到十亿线程规模的并行性的可伸缩性挑战。其次，程序员将面临在高度不均匀的系统结构中优化数据移动的局部性挑战，该系统结构具有存储器层次结构的相邻级别之间的带宽和延迟的数量级间隙。该项目的具体重点是开发编程模型，编译器和运行时，以解决未来HEC系统的上述挑战，由特定的众核架构指导，以确保实用性。该研究将在以下领域取得成果：1）基于X10语言过去经验的众核架构（如异步活动、位置和相位器）的新并行编程结构，但在本研究中将以C/C++而不是Java表现出来; 2）新的并行中间表示（PIR？s）和编译器优化的并行性和局部性; 3）一个新的线程虚拟机具有两个级别的并行性，同步粗粒度线程（SCT）和异步细粒度线程（AFT）;和4）评估的编程模型，编译器，和运行时的Cyclops C64众核系统，直接阐明了未来HEC系统面临的并行性和局部性的挑战。

The High End Computing (HEC) field is at a major crossroads due to the advent of many-core technology --- integration of tens and hundred processors (cores) on a single chip, heading to 1000 cores per chip in Exascale systems in the 2015-2020 timeframe. Unlike previous generations of hardware evolution, this shift in the hardware road-map will have a profound impact on future HEC software. First, the programmer will be faced with the scalability challenge of expressing and managing parallelism at the scale of millions to one billion threads in a single system. Second, the programmer will be faced with the locality challenge of optimizing data movement in a highly non-uniform system structure with order-of-magnitude gaps in bandwidth and latency between adjacent levels of the memory hierarchy. The specific focus of this project is on developing programming models, compilers, and runtimes to address the above challenges of future HEC systems, guided by a specific many-core architecture to ensure practicality. The research will deliver results in the following areas: 1) new parallel programming constructs for many-core architectures such as asynchronous activities, places, and phasers that build on past experiences with the X10 language, but will be manifested in C/C++ instead of Java in this research; 2) new parallel intermediate representations (PIR?s) and compiler optimizations for parallelism and locality; 3) a new thread virtual machine with two levels of parallelism, Synchronous Coarse-Grain Threads (SCTs) and Asynchronous Fine-Grain Threads (AFTs); and 4) evaluation of the programming model, compiler, and runtime on a Cyclops C64 many-core system that directly exemplifies the parallelism and locality challenges facing future HEC systems.