A New Standard

We test Apple’s A11 Bionic processor

With a physical design that is largely unchanged other than the addition of a glass back for wireless charging support, and featuring incremental improvements to the camera system most notably with the Plus version, the iPhone 8 and 8 Plus are interesting largely due to the presence of a new Apple SoC. The upcoming iPhone X (pronounced "ten") stole the show at Apple's keynote annoucement earlier this month, but the new A11 Bionic chip powers all 2017 iPhone models, and for the first time Apple has a fully custom GPU after their highly publicized split with Imagination Technologies, makers of the PowerVR graphics found in previous Apple SoCs.

The A11 Bionic powering the 2017 iPhones contains Apple’s first 6-core processor, which is comprised of two high performance cores (code-named ‘Monsoon’) and four high efficiency cores (code-named ‘Mistral’). Hugely important to its performance is the fact that all six cores are addressable with this new design, as Apple mentions in their description of the SoC:

"With six cores and 4.3 billion transistors, A11 Bionic has four efficiency cores that are up to 70 percent faster than the A10 Fusion chip, and two performance cores that are up to 25 percent faster. The CPU can even harness all six cores simultaneously when you need a turbo boost."

It was left to improvments to IPC and clock speed to boost the per-core performance of previous Apple SoCs, such as the previous A10 Fusion part, which contained a quad-core CPU split in an even arrangement of 2x performance + 2x efficiency cores. Apple's quad-core effort did not affect app performance beyond the two performance cores, with additional cores limited to background tasks in real-world use (though the A10 Fusion did not provide any improvement to battery life over previous efforts, as we saw).

The A11 Bionic on the iPhone 8 system board (image credit: iFixit)

Just how big an impact this new six-core CPU design will have can be instantly observed with the CPU benchmarks to follow, and on the next page we will find out how Apple's in-house GPU solution compare to both the previous A10 Fusion PowerVR graphics, and market-leading Qualcomm Adreno 540 found in the Snapdragon 835. We will begin with the CPU benchmarks.

First we have Geekbench 4, the popular cross-platform CPU benchmark which we run on all Android and iOS devices.

With the A11 Bionic Apple’s single-threaded dominance has never been more obvious, and this time the multi-threaded scores are not simply the result of scaling with the performance cores alone. The overall multi-threaded score of 10490 (the first time we've seen five digits from a mobile platform) represents such a significant leap over the single-threaded result that it is clear most – if not all – of the four efficiency cores can be utilized for compute-intensive work such as this benchmark.

Looking back on the A10 Fusion results from in our iPhone 7, we saw single/multi scores of 3486 and 5558, respectively, but even this (roughly 60% higher) multi-threaded scaling still compared very favorably to the high-end Snapdragon 835 which scored 6188 multi, and just 1844 single-threaded.

A breakdown of the results shows Apple leading in every category, with an emphasis on single-threaded dominance.

Apple's IPC is the key here, and their highly optimized operating system is another factor to consider. For its part Geekbench should still be providing as objective a look at cross-platform CPU performance as possible, and Apple's lead with the A11 Fusion has reached dizzying heights.

Now a look at the overall result from Basemark OS II:

More A11 Bionic CPU dominance. This is by far the fastest mobile processor we have tested, and it raises the question: how far from traditional CPUs is a mobile part like this? Geekbench can of course run on standard PC hardware as well as mobile platforms, and while there has been some debate as to direct comparisons of mobile and desktop/laptop hardware it's still the best we are going to be able to do today.

The Intel Challenge: Part 1

How does the A11 Bionic stack up against a dual-core Kaby Lake mobile CPU? Here is the iPhone 8 Plus up against an Intel Core i5-7300U (2-core/4-thread), with the Galaxy S8+ included for reference:

There you have it. The fastest smartphone CPU even beats a current-gen Intel mobile part (in Geekbench, anyhow). The A11 Bionic is slightly higher in single-threaded performance, with the large multi-threaded advantage clearly demonstrating all six cores at work (compared to the four threads of the Core i5). We will revisit this comparison with the graphics benchmarks on the next page, using the Ice Storm Unlimited cross-platform test.

On the next page we'll take a look at graphics performance from this new in-house GPU from Apple.