In context: For years, when Apple revealed a new A-series chipset, it would call it “the fastest we’ve ever made” and proceed to compare it with its predecessor. Every new SoC would see incredible performance gains that would look good during keynotes and manifest through both benchmarks and a lot of satisfied iPhone users. This year, however, the equation has changed to “frankly, the competition is still playing catch up with our chips.”
On the surface, the A15 Bionic in the new iPhones is an impressive bit of kit, with over 15 billion transistors etched using TSMC’s 5 nm process node. The CPU configuration has remained largely the same as that inside the A14 chipset, with two new high-performance FireStorm CPU cores paired with four IceStorm energy-efficient cores. Apple didn’t offer a performance comparison with the A14 and instead chose to highlight the fact that its new A15 chipset provides a 50 percent faster CPU performance when compared to the competition.
The new iPhone 13 and iPhone 13 Pro are both powered by an A15 chipset, but they have a small yet important difference: the GPU in the iPhone 13 Pro has one extra core for a total of five cores and support for a variable refresh rate. That said, the iPhone 13 is no slouch either, with Apple claiming 30 percent faster graphics performance — when compared to the competition. We’re starting to see a pattern here.
Apple has kept the same Neural Engine with a 16-core configuration, but now it can squeeze more performance out of it — 15.8 trillion operations per second, to be precise. The company again avoided a comparison with the NPU in the A14, which is capable of 11 trillion operations per second in machine learning tasks.
Other details are not clear at this point. For example, Apple said it integrated new video encoding and decoding capabilities into the A15 design but didn’t mention what those were, exactly. Many speculate that since the A14 already supports AV1 decoding, the A15 may well be able to accelerate AV1 encoding tasks.
Apple won’t say, but future A-series chipsets will bring smaller improvements that no longer warrant a comparison with their predecessors. In the case of the M1 SoC, it made sense for the Cupertino giant to make performance claims against Intel processors in the same class. With the A15 Bionic, the company is now drawing comparisons to flagship chipsets from competitors like Qualcomm, Samsung, and MediaTek.
There are three reasons for this behavior. The first is that A14 and A15 chipsets have a large enough lead over the competition that Apple can easily make that a selling point instead of the usual “our fastest yet” claim. This is why the company’s tune this year was, “frankly, the competition is still playing catch up to our chips. Not just from last year, but from two years ago.”
The second reason is related to diminishing performance gains expected with upcoming process nodes. For reference, TSMC says its N4 node will offer a lot more logic density, but the overall improvements will be a balancing act between up to a 15 percent speed gain and up to a 30 percent gain in energy efficiency. That means the A16 Bionic will probably be a more modest upgrade over the A15 or even the A14 Bionic.
Finally, Apple has been dealing with an exodus of talent that may have delayed plans for a more significant architecture upgrade. The most notable is the departure of chip designer Gerard Williams, who left Apple to co-found Nuvia with two Apple veterans. He was followed by several Apple engineers, and earlier this year, his company was snapped by Qualcomm for $1.4 billion.
As you’d expect, Apple wasn’t too happy about this development and dragged Williams into court for allegedly using the former’s trade secrets to boost his new venture. But the company has other things to worry about — its senior engineers keep leaving to form their own companies. As reported by Dylan Patel over at SemiAnalysis, some of them have joined a mysterious new startup called Rivos, which is working on a high-performance RISC-V CPU design, likely the first of its kind.
What this amounts to in the end is more competition in the custom silicon race, which is bound to gradually erode Apple’s leadership in performance per watt. Things are about to get interesting, so watch this space.