Particles At eXascale on High Performance Computers (PAX-HPC)

如果没有最先进的超级计算机，最近的许多突破是不可能的。例如，在2013年诺贝尔化学奖获得者中，超级计算机被用来开发强大的计算程序和软件，来理解和预测复杂的化学过程，或者在2017年诺贝尔物理学奖中，超级计算机帮助进行复杂的计算，以探测迄今理论上的引力波。艾级系统的出现是这一演变的下一个戏剧性步骤。艾级超级计算将在英国科学的广泛领域实现新的科学努力，包括先进材料建模、工程学和天体物理学。例如，以越来越逼真的方式解决原子和电子结构以解决主要的社会挑战--电池、电解电池、太阳能电池、计算机、照明和医疗解决方案的量子力学详细模拟和指导设计，以及实现对喷气式发动机中的瞬变(如鸟击)的端到端模拟，到海啸淹没一系列防御墙的模拟，或者在宇宙尺度上理解宇宙。提供精确描述这些具有挑战性的问题的详细程度，可以使用基于粒子的模型来实现，这些模型以复杂的舞蹈进行交互，可以可视化或分析以查看我们的自然模型在各种情况下将如何反应。要模拟像概述的那样复杂的问题，粒子交互的方式必须灵活并针对问题量身定做，并且需要大量的粒子(和/或复杂的交互)。这项提议面临的挑战是高效地计算大量计算机核心上相互作用的粒子。粒子的密度在不同的位置可能会有很大的差异，因此必须找到一种方法，使计算引擎具有类似的工作量-将开发新的算法，将工作分配到不同类型的计算引擎，并用于开发和运行现实世界挑战的前沿模拟。购买和运行艾级系统的成本都很高，因此在用户使用艾级系统之前，必须开发适当的软件。根据定义，艾级超级计算机将比英国目前的设施强大三个数量级，这将通过更多内核和加速器(例如基于游戏显卡)实现。计算机能力的这种转变既代表了预期的硬件复杂性和异构性的增加，也代表了核心之间通信量的增加，这将阻碍英国当前超级计算机上使用的算法。在充分利用硬件架构之前，我们的许多(如果不是全部)软件包都需要进行重大更改。该项目的研究人员是国际领先的专家，他们开发(使新科学成为可能)和优化(使模拟更有效)最先进的基于粒子的软件，用于在国内外的超级计算机上运行模拟。我们开发的软件在学术界和工业界都有使用。在我们的项目中，我们将开发解决方案，并在我们的软件中实施这些解决方案，重要的是，培训研究软件工程师成为利用亿级超级计算机进行科学研究的国际领先技术。

Many recent breakthroughs would not have been possible without access to the most advanced supercomputers. For example, for the Chemistry Nobel Prize winners in 2013, supercomputers were used to develop powerful computing programs and software, to understand and predict complex chemical processes or for the Physics Nobel Prize in 2017 supercomputers helped to make complex calculations to detect hitherto theoretical gravitational waves. The advent of exascale systems is the next dramatic step in this evolution. Exascale supercomputing will enable new scientific endeavour in wide areas of UK science, including advanced materials modelling, engineering and astrophysics. For instance, solving atomic and electronic structures with increasing realism to solve major societal challenges - quantum mechanically detailed simulation and steering design of batteries, electrolytic cells, solar cells, computers, lighting, and healthcare solutions, as well as enabling end-to-end simulation of transients (such as bird strike) in a jet engine, to simulation of tsunami waves over-running a series of defensive walls, or understanding the universe at a cosmological scale. Providing a level of detail to describe accurately these challenging problems can be achieved using particle-based models that interact in complicated dance that can be visualised or analysed to see how our model of nature would react in various situations. To model problems as complex as outlined the ways the particles interact must be flexible and tailored to the problem and vast quantities of particles are needed (and or complicated interactions). This proposal takes on the challenge of efficiently calculating the interacting particles on vast numbers of computer cores. The density of particles can be massively different at different locations, and it is imperative to find a way for the compute engines to have similar amounts of work - novel algorithms to distribute the work over different types of compute engines will be developed and used to develop and run frontier simulations of real-world challenges. There is a high cost of both purchasing and running an exascale system, so it is imperative that appropriate software is developed before users gain access to exascale facilities. By definition, exascale supercomputers will be three orders of magnitude more powerful than current UK facilities, which will be achieved by a larger number of cores and the use of accelerators (based on gaming graphic cards, for example). This transition in computer power represents both an anticipated increase in hardware complexity and heterogeneity, and an increase in the volume of communication between cores that will hamper algorithms used on UK's current supercomputers. Many, if not all, of our software packages will require major changes before the hardware architectures can be fully exploited. The investigators of this project are internationally leading experts in developing (enabling new science) and optimising (making simulations more efficient) state-of-the-art particle-based software for running simulations on supercomputers, based here and abroad. Software that we have developed is used both in academia and in industry. In our project we will develop solutions and implement these in our software and, importantly, train Research Software Engineers to become internationally leading in the art of exploiting exascale supercomputers for scientific research.