Following the launch of Apple's (NASDAQ:AAPL) iPhone 6s, a new rumor hit the Web regarding the A10 processor that is expected to arrive in the company's next-generation iPhone. This rumor, which comes from a post on Weibo, claims the following (note that this is a translation):
Apple is developing the next generation A10 architecture, will focus on the development of multi-threading, up to six core is 10nm or 14nm, Samsung, TSMC, Intel (NASDAQ:INTC) 14nm process also rob on the order
As you can tell, the translation isn't perfect but the gist of the post is that Apple's next-generation A-series processor will feature "up to six cores" -- a substantial boost from the two processor cores found inside of the A9 chip.
Does this rumor make any sense or is it purely bogus? Let's take a closer look.
Six cores? Not likely.
Right off the bat, I can tell you that there's essentially no chance that Apple will include six physical CPU cores in a next-generation A-series chip. The A9 is a dual-core processor, and it is so for good reason: Phones are very thermally constrained so it makes more sense to spend what power budget is available to the chip on wringing out as much per-core performance as possible.
That being said, I have seen it suggested elsewhere that what the poster here actually meant to say is that the A10 will have three cores, but each core will include simultaneous multi-threading -- a technique that allows a single processor core to "act" as a multi-core processor, allowing for better utilization of a chip's execution resources.
Although I doubt that the A10 will be a six-threaded chip, I see the following as possible: The A10, which should go into the next iPhone, remains a dual-core chip, but each CPU core can support two threads of execution, making it a dual-core/quad-threaded processor. The A10X, which should find its way into the next iPad Pro, then, would be a triple-core/six-threaded processor.
Would simultaneous multithreading make sense?
According to Intel -- which has implemented simultaneous multi-threading (Intel calls it "hyperthreading") in its mainstream processors for many years now -- this technique "significantly boosts performance for very little power cost." Indeed, the company says that the speedup from simultaneous multithreading (which Intel markets as "hyperthreading") can be between 20% and 30%.
Additionally, this speedup -- per Intel -- comes at a "less than 5% die size and power consumption increase compared to a single processor package." Given that the CPU cores represent a fraction of Apple's A-series chip area, I'd expect the total die size impact of simultaneous multithreading in an A-series chip to be quite small.
I think that if Apple is looking to boost the multithreaded performance of its A-series chips, implementing this technique could be a sensible alternative to adding more cores.
Adding more cores is probably easier and could lead to higher peak multithreaded performance than implementing simultaneous multithreading and keeping core counts the same. However, simultaneous multi-threading looks like it could be the more energy and area efficient way (the latter of which implies cost efficient) of getting more multi-threaded performance in a power-constrained mobile device.