Shinji Sumimoto

The International Exascale Software Project roadmap

Over the last 20 years, the open-source community has provided more and more software on which the world’s high-performance computing systems depend for performance and productivity. The community has invested millions of dollars and years of effort to build key components. However, although the investments in these separate software elements have been tremendously valuable, a great deal of productivity has also been lost because of the lack of planning, coordination, and key integration of technologies necessary to make them work together smoothly and efficiently, both within individual petascale systems and between different systems. It seems clear that this completely uncoordinated development model will not provide the software needed to support the unprecedented parallelism required for peta/ exascale computation on millions of cores, or the flexibility required to exploit new hardware models and features, such as transactional memory, speculative execution, and graphics processing units. This report describes the work of the community to prepare for the challenges of exascale computing, ultimately combing their efforts in a coordinated International Exascale Software Project.

Dynamic home node reallocation on software distributed shared memory

This paper proposes a dynamic home node reallocation mechanism in a sofware distributed system memory system to reduce the communication overhead at the memory barrier synchronization point. The mechanism has been implemented in a software distributed memory system called SCASH. The evaluation results using the LU application of SPLASH2 running on a PC cluster show that the execution performance using the mechanism is better than using static home node allocation mechanisms including an optimal case of up to 8 node execution.

Parallel C++ programming system on cluster of heterogeneous computers

A parallel programming system, called MPC++, provides parallel primitives such as remote function invocation, a global pointer, and a synchronization structure using the C++ template feature. The system has run on a cluster of homogeneous computers. In this paper, the runtime system is extended to run on a cluster made up of a heterogeneous computer environment. Unlike other distributed or parallel programming systems on heterogeneous computers, the same program in the homogeneous environment runs in the heterogeneous environment in this extension.

Xruntime: A Seamless Runtime Environment for High Performance Computing

Most HPC clusters are now based on an x86 architecture and Linux. In a Grid consisting of such clusters, users might think that a single executable file, a data set, and a single job script will work in all cluster environments. However, due to the lack of interoperability of MPI library implementations, file systems, and batch job systems, users need to be conscious of the runtime environments over the Grid. In order to overcome such differences, we propose a runtime environment called Xruntime consisting of the following three components. MPI-Adapter is middleware between the user program and an MPI implementation to make it possible to execute a single executable code on different MPI implementations. Catwalk is transparent file staging middleware that makes remote files accessed by an application visible as if they were located in the local system. Xruntime allows a user to use various clusters with single batch job script language the user is familiar with, without learning other batch job script languages used on other clusters.

GigaE PM: a high performance communication facility using a Gigabit Ethernet

A high performance communication facility, called theGigaE PM, has been designed and implemented for parallel applications on clusters of computers using a Gigabit Ethernet. The GigaE PM provides not only a reliable high bandwidth and low latency communication, but also supports existing network protocols such as TCP/IP. A reliable communication mechanism for a parallel application is implemented on the firmware on a NIC while existing network protocols are handled by an operating system kernel. A prototype system has been implemented using an Essential Communications Gigabit Ethernet card. The performance results show that a 58.3 μs round trip time for a four byte user message, and 56.7 MBytes/sec bandwidth for a 1,468 byte message have been achieved on Intel Pentium II 400 MHz PCs. We have implemented MPICH-PM on top of the GigaE PM, and evaluated the NAS parallel benchmark performance. The results show that the IS class S performance on the GigaE PM is 1.8 times faster than that on TCP/IP.