HPC 2014-15 | Processors


system in June 2014 delivered just 4.4 Gflop/s per watt demonstrating that although the Adapteva technology is early in its evolution, the approach is one that can deliver significant value as the industry seeks to radically reduce the power consumption of HPC systems. An alternative extreme multicore


implementation is the MPPA MANYCORE architecture from Kalray. Te MPPA-256 processor has 256 cores per chip that can deliver 11 Gflop/s per watt on a single precision matrix multiply. A 3.6 GHz commodity processor delivers half of this performance but uses three times as much power. FPGAs offer tremendous potential for high


performance within a very low power budget, but at the cost of programming complexity. Oskar Mencer of Maxeler Technologies claims that they could build what he calls an ‘Exascale equivalent’ system in just a handful of cabinets. Tis would be a system tailored for a specific class of applications, rather than a general purpose HPC system. FPGA manufacturer Altera has been


promoting the use of OpenCL to generate host code as well as FPGA kernel code, a process that could make FPGAs more easily accessible to the general-purpose HPC market, although there is still a lot of work to be done in this area. In order to provide more functionality for HPC users, Altera is also developing floating-point arithmetic engines and DSP blocks that can be included in an FPGA-based processor design. Microsoſt has been experimenting with


FPGAs to support its Bing search engine. Te Microsoſt Research Group built a system called Catapult that adds an Altera FPGA with 8GB Ram to each of 1,632 standard servers. Te


FPGAs handle only one part of the search process, that of ranking pages that match a search. Te experiment has been a great success, almost doubling performance at an increased system cost of only 30 per cent, and an increased power budget of 10 per cent, so the system will go live in 2015. Microsoſt sees this work not as a one-off, but as a demonstration of the potential for FPGAs to deliver cost effective accelerated computing. Even Intel acknowledges the value of FPGAs, by offering a hybrid Xeon/FPGA on a single chip, admitting that for certain tasks an FPGA can outperform a Xeon processor by a factor of 10. Texas Instruments has been dabbling in HPC


for a few years, with its DSPs being deployed in the energy efficient nCore BrownDwarf supercomputer alongside ARM processors.


“FPGAs offer tremendous potential for high performance within a very low power budget, but at the cost of programming complexity”


TI also supplies chips that combine 4 ARM cores and an integrated DSP for HP’s Project Moonshot. While we are looking at radical approaches,


the wackiest one worthy of a mention is D-Wave, which builds systems based on quantum computing. Tis will never be a mainstream technology (aſter all, it runs at very close to absolute zero, or -273.13 degrees Celsius), but it is able to solve some classes of problem much


Nvidia Tesla K40 GPU Accelerator


quicker than traditional technologies (such as discrete optimisation problems) by analysing many potential solutions at the same time. D-Wave systems won’t replace the majority of HPC systems, but as the technology matures it could provide an important component of large scale HPC infrastructures.


Conclusion It took decades from the first discussion on killer micros to today’s position where commodity processors dominate the HPC landscape, so we should not expect the next technology transition to happen overnight. In the long term, the commodity processors that drive the internet and giant databases are unlikely to meet the compute power per watt requirements of future HPC systems. But will they continue to provide the backbone of HPC systems with support from accelerators? Or will a more radical approach win the day? Programming complexity will make it hard for some of the emerging technologies to make a quick breakthrough to mainstream HPC, but anyone who thinks that Exascale systems built from an evolution of today’s commodity processors and accelerators will be easy to program is fooling themselves. Te majority of today’s HPC systems are


clusters of x86 servers, with each processor having a handful of cores. Tis will not be the case in 10 years’ time -- but the question about which technology will be dominant has not yet been answered. Some of the solutions that are attractive from a performance per watt perspective (FPGAs, DSP, massively parallel devices) are not widely considered today because they are difficult to program. Perhaps the next big breakthrough in HPC will not be in hardware, but will be in soſtware tools that make some of the more exotic, but energy efficient, devices more accessible to the average HPC programmer. l


With more than 30 years’ experience in the IT industry, initially writing compilers and development tools for HPC platforms, John Barr is an independent HPC industry analyst specialising in technology transitions.


8


Intel Nvidia


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40