ARM`s James Bruce on Exynos, big.LITTLE and SoC Design, Part I
James Bruce, Lead Mobile Strategist of ARM August 27, 2012
James Bruce, lead mobile strategist for ARM®, is a devoted gadget guy with a long career in mobile technology that has made him an excellent source for questions about the world of mobile processors. James took the time to speak with us about ARM, Samsung Exynos and the semiconductor industry at large. In fact, James had so many valuable insights that we had to turn the post into a two-part series! We hope you enjoy the exchange as much as we did.
ARM Lead Mobile Strategist
How has ARM come to be the industry standard for building mobile application processor (AP) structures?
In two fundamental ways: Through improving power efficiency (i.e. doing more with less) and through the ARM business model. In the past, a lot of people designed processors for use by their own companies, which had major challenges. It’s very expensive to actually design and build out your own processor, and you also have to worry about compatibility across the industry.
Now that we’ve developed a common, industry-standard CPU, system-on-chip (SoC) companies can build off of that blueprint much more easily. SoC companies like Samsung can now focus on designing their Exynos chips, rather than spending a lot of time and resources trying to design and build their own CPUs. ARM was one of the companies at the forefront of this changeover in business models, which is part of the reason why it is now regarded as the industry standard for mobile processors.
How do ARM and Samsung Exynos mutually benefit from their partnership? Are there plans laid out for continued collaboration?
Samsung is an incredibly important partner for ARM because it works with leading-edge SoC technology, which in turn contributes to ARM’s ability to deliver the best possible IP. There has been some great activity in the Exynos family of chips over the past few years, notably with the Exynos 4 Quad ARM® Cortex™-A9 and the Exynos 5 Dual Cortex™-A15 mobile APs. The Exynos platform has been excellent in showing the performance of our Mali™ series of GPUs. The second-gen Mali™-T600 series represents a range of new graphical technologies, so it should be interesting to see the (potentially Exynos-powered) mobile devices that make use of this series in the future.
What role will big.LITTLE technology play in the future of mobile APs?
I think we are going to see big.LITTLE processing become one of the fundamental technologies in SoC design in the coming few years. Smartphone advancement is going to become increasingly difficult as consumers expect more out of their mobile devices. The important thing with big.LITTLE is that it allows you to scale computing needs to the task at hand. In future generations of smartphones, big.LITTLE technology will give the system the ability to operate on whichever size processor is appropriate for the desired action.
For example, if you’re typing a text or updating your email, you don’t need that much CPU performance, so the Cortex™-A7 processor will be sufficient; whereas when you want to render a PDF document or several webpages, you need significantly more CPU performance, such as that offered by the Cortex™-A15 processor. Not only does this approach optimize performance, it ensures a much greater level of power efficiency than was possible with previous technologies.
Exynos5 Dual Soc
What is the biggest misconception about SoC technology?
This may sound funny coming from someone at ARM, but the biggest misconception about SoC technology is that it’s just about the processor. If you actually look at Samsung Exynos’s design work, the processor is very important, but it’s what Samsung builds out around it that really counts – the GPU, video encoder, image processor, audio engine and other components. There is so much within an SoC that you really have to look at the whole to understand the extent of a chip’s capabilities. It’s not as simple as focusing on just one component.
Using Exynos low-power processors as a reference, which aspects of SoC design have the greatest impact on power efficiency?
One of the keystones is actually designing your SoC to not do anything, which may sound counterintuitive. Part of what the Exynos design team focuses on is turning off as many functions as possible when they are not in use. Once again, this depends on the task at hand and relates back to big.LITTLE processing. If none of the tasks at hand require a high-performance processor, it’s much more efficient to “switch off” that processor and use the smaller, more power-efficient processor instead.
Image processing is a good example of this. The Mali™-T600 series of GPUs is the first in the Mali line to offer GPU Computing capabilities. If you process images on the GPU Compute rather than on the CPU, you’re probably achieving three to five times greater power efficiency. By taking over these types of parallel-intensive tasks, the GPU helps the overall SoC realize significantly greater power savings.
In part two of this interview, James Bruce will discuss the latest generation of ARM® Mali™-T600 GPUs, as well as the future of the semiconductor industry.