In the same breath as reporting that the Ohio Supercomputer Centre in Columbus has installed an eight-processor 80860-based PVS Power Visualisation System, IBM Corp has criticised traditional supercomputers, from the likes of Cray Research Inc, for their inferior data throughput capabilities. According to IBM, traditional supercomputers, in spite of their power, can’t adequately model more than a few of the smallest scientifically interesting molecules. IBM refers to a relentless computational carnivore, the so-called N4 barrier, as blocking progress in quantum chemistry. N4 is said to dictate that to double the size of a molecule it simulates, a computer must perform 16 times as many calculations. Because of N4, IBM claims, computer models of all but the smaller molecules are limited to the same sort of incomplete and hazy views as offered by astronomy before space probes were launched. Even more frustrating, it says, the power of many supercomputers, such as the Ohio centre’s Cray Y-MP 8-864, can’t be applied efficiently to quantum chemistry problems, due to an inadequate data throughput.
Balanced for data visualisation
Meanwhile, says IBM, PVS is balanced for data visualisation that is, all its elements have been designed to speed data without bottlenecks. PVS is scalable from eight to 32 Intel 80860 processors in parallel – each assigned 16Mb local memory and able to pool 1Gb of shared memory for large problems (CI No 1,918). Communication between the processors and global memory is sustained at 1.28Gbps. PVS delivers images rather than just numbers, so that scientists can move towards interactive simulation and exploration – the ability to view complicated calculations in progress and alter them on the fly. PVS peak processing speed is rated at 2,500 MFLOPS. It supports a HIPPI high-performance parallel interface channel that can transmit data at up to 100Mbps. IBM claims that the PVS can calculate as fast as a small supercomputer while moving data in and out speedily enough to challenge the N4 barrier – up to 55Mbps compared to 9Mbps for the Y-MP – accessing up to 170Gb of data from an IBM Disk Array Subsystem. In addition, IBM claims, PVS can move large blocks of data in and out of its large internal memory, so being able to perform crucial quantum chemistry operations up to five times faster than the Cray. The Ohio Supercomputer Centre has two goals for its PVS installation, says centre director Charles Bender: to adapt current chemistry programs to PVS’s parallel architecture, so it can evaluate how the more highly parallel systems of the future will work in computational chemistry and biology; and to tackle some of the so-called Grand Challenge problems in these fields, such as fuel synthesis and DNA genetic molecule modelling. So far, the Ohio scientists have converted the Hondo computational chemistry application for PVS and are working on three other major programs – Columbus – developed at the Centre – ACESII and GAMESS. More powerful PVS boxes are said to be in the works.
