Will Finfets Affect ARM?
With Intel finally getting its finfets off the ground, it seems apposite to ask exactly what this process will achieve.
And who better to ask than Mike Bryant, CTO of Future Horizons?
“The Trigate transistor designer can choose to improve any parameter but the technology limits are 37% faster OR 50% more dynamic power efficient OR 90% less static leakage, thus in theory if you want the same speed and leakage, you get 50% less dynamic power. Or if you accept the same dynamic and static (leakage) power then your circuit runs 37% faster. Or for the same speed and dynamic power you get 10 times less leakage.”
“Obviously you actually choose some middle ground of all three and at the moment Intel have chosen a single option that is best for their MPUs but the optimal solution for SoCs is still being discussed,” adds Bryant, “once decided this will appear next year in the Silvermont processor.”
Next year is slated for the introduction of Atom-based handset SOCs from Intel out on its 22nm finfet process, will that make Intel’s wireless chip-sets competitive?
No, says ARM’s CEO Warren East. “We expect the 22nm process will give them some advantage in power consumption, but whether that advantage is sufficient to make them competitive remains to be seen,” Warren East told me a couple of weeks ago, “they’re saying the process will give them 20% more power efficiency but they’re a lot more than 20% less efficient than ARM.”
Asked the same question, Mike Bryant replies: “Unlike in small systems where it is key, in big systems, which smartphones most definitely are nowadays, the instruction set used is far less relevant with only 10% to 15% of power dealing with it. So even if ARM waved magic dust on their instruction set, which isn’t perfect anyway, they can only optimise 10% to 15% of the power used. More power goes in moving data around the chip, and most goes to moving data on and off the chip to memory and peripherals.”
“ARM programs can actually use a few percent more codespace than Intel but let’s say they are the same,” adds Bryant, “next of course the data either processor has to be moved around – be it pictures, voice data, HTML or just the call set-up protocol, is identical for each processor. Finally the video data has to be transferred onto the display and for all the hype ARM’s Mali is about the same as GPUs from Intel or Nvidia, though there are slightly more efficient solutions from Imagination Technologies or Qualcomm’s Adreno.”
“So for a pure ARM system against a pure Intel system, 85% of the power usage is independent of the processor instruction set and dependent purely on the process technology,” concludes Bryant.