Computers and the Energy Factor
For a long time, the only interesting thing about computers was how fast they were. Today, how much energy they consume is just as important. Power consumption plays a key role in computing centres and server farms managing the rapidly growing amounts of data on the Internet. They already consume more energy than worldwide air traffic. Researchers at Jülich are working on different aspects of the “green” information technology of the future
Information and communications technologies account for more than ten percent of the total energy consumed in Germany – and counting. Electronic devices increasingly dominate our everyday lives. Chips in these devices are becoming more and more powerful, and as a consequence, their appetite for energy is also increasing. Researchers at Jülich are looking for energy-efficient solutions on different levels: from tiny components to computer architectures and the energy management in supercomputer centres.
A Look at New Materials
Conventional silicon technology currently used to produce chips is coming up against its limits. New electronic materials promise revolutionary progress for coming computer generations. These materials exhibit unusual effects such as multiferroicity, memristive behaviour, and spintronics, which are being intensively investigated. Many of these properties were only discovered in the past few years and are now becoming increasingly controllable. Processors and storage elements using these phenomena could be significantly faster and more energy-efficient than components currently employed.
Although the approaches and applications differ considerably, the materials used are very similar. Metal oxides and higher chalcogenides are normally used due to their chemical stability and a range of electronic effects.
Memristors: Energy-Saving Miniature Storage
An innovative concept for the fabrication of future computers includes novel components, namely memristors, connected with each other in a special way. They are a focus of research in the Jülich working group headed by Prof. Rainer Waser from the Peter Grünberg Institute (PGI-7/Electronic Materials). Their results have been published in leading journals, such as Nature Materials in April 2010.
Memristors are tiny electronic components in which high resistance can be switched to low resistance and back again using ultrashort pulses of voltage. They are interesting as a fast memory, because in contrast to the working memories used today, the data stored on memristors is not lost as soon as the computer is switched off. Such memristive storage also has other advantages. The energy required to write to these new memories is less than a hundredth of that required by today’s flash memories, used for example in USB flash drives.
Memristive storage is not only able to store information, but compared to conventional transistors, it also processes information very efficiently. Energy can be saved, for example, by combining working memory and the actual processing unit, which are usually separate components and require large amounts of energy and computing time to communicate with each other.
In addition, memristors are not only able to differentiate between one and zero, but also a range of intermediate states. This opens up entirely new opportunities. For example, memristive cells can imitate neural networks modelled on living neurons, which process information according to entirely different principles than normal processors. At the same time, their energy efficiency is very high.
Computer Architectures for Supercomputers
Supercomputers are now a permanent fixture in addition to theory and experiment in almost all fields of research. The progress of knowledge also means that enormous computing capacities are required for simulation, for example to model biological organs, calculate multi-layered climate models and study the structures of complex materials.
Scientists at the Jülich Supercomputing Centre (JSC) cooperate with companies such as IBM and Intel in order to make supercomputers that are a thousand times faster than JUGENE a reality in research by 2020. Their computing power will reach more than one exaflop, or a quintillion (1018) operations per second: 1,000,000,000,000,000,000.
At the same time, a computer of this class should be much more energy-efficient than today’s computers. Otherwise, each computer would require its own power plant. Ideally, energy efficiency would be improved by a factor of 1,000. Central aspects in the development of a supercomputer that is compatible with environmental and economic requirements are new concepts for the computer architecture, for the software, and for cooling.
Forschungszentrum Jülich cooperates with a number of partners pursuing a variety of alternative hardware and software concepts. Together with IBM, Jülich has established the Exascale Innovation Centre (EIC). At the European level, Jülich coordinates the EU project DEEP (Dynamical ExaScale Entry Platform) that involves Intel, ParTec and twelve more partners from eight European countries. The project was launched in December 2011 and is funded with € 8 million from the European Commission.
The DEEP project benefits from close collaboration between Jülich, Intel and ParTec under the umbrella of the ExaCluster Laboratory. The laboratory was established in 2010 and focuses on novel system architectures and software tools developed specifically for cluster computers.
As part of the Fit4Green project, in which Jülich plays an active part, a software was created that automatically switches off supercomputer components that are not in use. As a consequence, computers require 6 to 16 % less energy than they usually do to work through their jobs. The tool can also be used for large servers, for example for cloud computing, thus achieving even greater savings in distributed computing structures.
Jülich's new supercomputer JUQUEEN was put into operation in June 2012. JUQUEEN has no less than 131,072 cores and a peak performance of 1.6 petaflops. It is based on an IBM BlueGene/Q architecture and will be expanded further in the course of this year. Supercomputers of the same type currently top the Green500 list of the world’s most energy-efficient supercomputers at two gigaflops per watt. Jülich scientists have been testing the new series from the very first prototypes and are cooperating with partners from IBM in the Exascale Innovation Centre to use future systems efficiently for research.
However, it is actually the human brain that is still the most energy-efficient “supercomputer”, with an unbelievably low energy consumption of just 30 watts – less than a conventional incandescent light bulb. Its performance is based predominantly on a multitude of parallel connections between neurons. A deeper understanding of this human organ by means of simulations on supercomputers could help to transfer the human brain’s natural energy efficiency to computers.
Memristors and the results of Prof. Waser’s working group (press release of 18 April 2010)
Article in Nature Materials: "Complementary resistive switches for passive nanocrossbar memories"
Peter Grünberg Institut – Elektronische Materialien (PGI-7)
Collaboration with partners:
Launch of the DEEP exascale project (press release of 15 November 2011)
Video: 1st Jülich Lecture: "Overcoming the barriers to Exascale through Innovation" - Stephen S. Pawlowski (Intel)