Do we really need eight core processors?

July 30, 2013
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With Samsung upgrading its Exynos 5 Octa to make use of all eight cores at once, and MediaTek recently announcing its own true eight core processor, it looks like octa-core processors could soon become the new norm in high end mobile devices. But do we really need all those cores?

There are obviously some benefits to going wide rather than aiming for brute force, such as increased performance when multitasking and less power consumption when performing day to day tasks. Eight core processors would certainly give us more potential for the former, but will start eating into those ever so vital energy savings, compared with equivalent dual or quad-core chips.

We have to consider if we really need more parallel processing power in our mobile devices? I find it doubtful that many, or indeed any, of us will ever be performing so many tasks at once that a quad-core can’t keep up. I’m not sure that the multi-threaded performance argument really stands up in favor of eight-cores for mobile devices. Furthermore, when it comes to more demanding applications, like gaming, you’re often better off with two or so more powerful cores to do the legwork.

Looking at the other beneficial aspect of multi-processors for mobile devices, lower power consumption, adding in more and more cores means more transistors on chip, and that results in more heat and power consumption, even when under-clocked in a semi-idle state.

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MediaTek may be offering a true eight core chip, but that’s four more cores drawing current just to keep them ticking over.

MediaTek and Samsung are already acutely aware of this problem, hence why they are opting for low power cores and innovative architectures like big.LITTLE, to help keep the power consumption to a minimum. But there’s no escaping the fact that high performance requires more power, so these chips are already compromising just to squeeze in more cores. And that’s not even mentioning the additional financial costs in terms of wafer space and wastage.

According to sources inside Taiwan’s handset supply chain, this is the main reason why handset manufacturers won’t be rushing out to build eight core devices with the current technology. They simply don’t see any performance or power consumption improvements over existing quad-core chips, yet are likely to be more expensive. Supposedly, quad-core devices will continue to be the mainstream over the next 1-2 years.

ARM big.LITTLE technology shows the truth behind the Exynos 5 Octa. Side by side quad-cores, not a true octo-core.

On paper, ARM’s big.LITTLE MP architecture offers a good balance of peak performance and low energy states, but the design is still having teething problems balancing its workload.

Instead, technological improvements like smaller 14nm manufacturing techniques, new architectures, such as lower power Cortex A50 cores combined with heterogeneous architectures, and more intelligent schedulers will be key to driving processor technology forward, which could eventually lead to octa-core chips becoming much more viable.

To me, it seems like eight core hardware still has a way to go before it’s really suitable, or even needed for smartphones, hence the lack of early adopters. I’m hesitant to say that octa-core won’t become commonplace eventually, after all, consumers seem to be in pursuit of ever more performance. But it seems that we’re a few years off before the technology has matured enough to be truly useful.

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