ARM’s big.LITTLE processing technology is coming of age

by: LucianJune 13, 2012
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ARM has been getting a lot of praises on their idea for the big.LITTLE technology, because it shows them not only a leader in mobile chip performance, but they are moving forward with higher and higher performance. Their chips still remain low-power overall and in the future they claim they will achieve this through big.LITTLE technology.

Big.LITTLE means they are going to pair up a very low-power in-order CPU like Cortex A7, with their most powerful out-of-order CPU yet, the Cortex A15. This should work much in the same way that Nvidia’s 4+1 technology works, with their extra core companion. The difference is that Nvidia used the same CPU for both types of processing, which means that for low-end tasks, Cortex A9 was a bit of an overkill, even if it had a low clock frequency of 500 Mhz.

So the difference between the power consumption ranges, would be more like between a low-end phone and a high-end phone, which shouldn’t be too big. This could explain in part why Tegra 3 is not exactly the most battery-saving CPU right now, with the other part coming from the fact that it’s a quad core processor made at 40nm compared to the competition which is already at 32nm or 28nm. In contrast, big.LITTLe uses one (or two) very low-power CPU like the Cortex A7, and the high-performance Cortex A15; together they are meant to keep the power consumption at least as good, if not better, than previous generations and chip configurations.

ARM has worked with many partners already to bring big.LITTLE to market from software companies like Linaro, to manufacturers who have already licensed it: Samsung, LG, TI, Broadcom, Freescale, ST-Ericsson, Hisilicon and Renesas. We can expect devices with big.LITTLE to arrive at the end of this year at the earliest. Cortex A7’s schedule is a little behind that of Cortex A15, so although we may see one or two chips with Cortex A15 from Samsung and TI this year, we might not see one with A7 until the first half of next year. I surmise this is unless Samsung somehow manages to do it this year (perhaps for their Nexus device this fall).

Cortex A15 and big.LITTLE are the next-generation processing technologies we should be expecting in our next phones and tablets, which should unlock a lot of raw performance, getting ever closer to the performance of a good enough PC or notebook.

  • Gabba

    So lemme see if I have this right – pure A15’s are expected sooner than big.LITTLE, which employ A7’s and A15’s, right?

    • I think big.LITTLE is coming with Cortex-A15 although for example TI implements their own style of big.LITTLE using 2 Cortex-M4 “small co-processors” instead of Cortex-A7 yet. My guess is Exynos5 uses big.LITTLE, maybe that info is public already and I forgot about it. Also check my interview with Paul McKenney of IBM he talks about some of the work they are doing at Linaro to prepare for support for big.LITTLE, it’s high-level ARM Linux Kernel hacking stuff.