ICT
Issue No. 40 - March 2012
A few years ago, a better computer was simply a faster computer. To measure a computer’s performance, we would ask: how many operations can this processor perform in a given time? And the answer can be quite high; we tend to measure it in billions of operations per second. While performance is still very important, another feature is receiving its own share of attention: energy efficiency.
U sing less energy can be more environmentally friendly, but that is not the only factor pushing us towards energy efficiency. Efficiency enables us to tap away on our laptop for five straight hours without having to plug in, instead of the one or two hours we got a couple of years back. And while I would not mind a bit of extra heating during winter, I would rather have my laptop battery lasting longer than have it warming my legs, to say nothing of the noise the fan makes to cool the processor because of the heat generated. Efficient computers are cooler computers, allowing us to watch video clips, or whole films, without the annoying whirring from the laptop fan.
At this end, processing capability is not limited by the number of processors that can fit inside the room, but by how fast the cooling system can remove the generated heat. It is true that we can get quadrillions of processor operations for each kilowatthour, but the number of operations required on a typical server farm is really very high.
System software can also benefit from good engineering. If someone were to get a new laptop with a good operating system, and replace that good operating system with an ageing one, they would find that the batteries last less. This indicates that today’s operating systems are getting better at using inbuilt power-conserving facilities in processors.
When observing that computer hardware is getting faster, some engineers like to quip that at the same time, computer application software is becoming more complicated and slower, such that the end user does not see any improvement in speed.
The benefits of energy efficiency become most important at the two opposite ends of the computer scale: the very small and the very large. Today’s smart phones are nothing less than small computers, complete with web browsers, games, and media players, all of which can be processor intensive and power hungry. Supporting all of these applications using the small battery that can fit in the slim phones would be impossible without the huge improvements in energy efficiency we have seen in recent years.
At the other end of the scale, we have the server farms, large clusters of processors that handle our communications systems, process our information, and provide our online services. Here the problems are the heat produced by the processors and the power bills, not to mention the hardware damage that can result owing to over-heating.
Improving energy efficiency by 10% would allow 10% more processing to be performed at the same cost and in the same space.
To obtain the higher efficiency we are striving for, good design is required at all levels of computer engineering, all the way from microelectronic circuits to the software applications that run on a mobile phone. Processors have been improving, and although the switching speed of the transistor is not improving at the exponential rates of the past decades, the amount of energy required per processor operation is still going down rapidly thanks to advances in microelectronic engineering.
Many technological advances have found their way into processors; for example, today’s processors are much better at turning the power down when they are doing light work.
However, there is now a clear shift in software construction towards clean, simple and better interfaces and functions, and towards building software that does less work behind the scenes.
Energy efficiency has now become one of the most important considerations for good computer engineering. There is still a lot of research to carry out in both academic and industrial settings, which will result in both cost and functionality benefits.
Trevor Spiteri is an assistant lecturer with the
Department of Communications and Computer
Engineering within the University of Malta since
2008, after working for six years in the local industry.
His research interests mainly involve reconfigurable computing, and he is currently working on a Ph.D. on reconfigurable hardware for multimedia compression applications at the University of Bristol, UK.
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