The Pixel 6 and Pixel 6 Pro we officially unveiled yesterday. Alongside them, we got confirmation that they run the fascinating new Google Tensor SoC — here’s everything different from anything else currently out there.
One of the most peculiar differences, as predicted by leaks, is the arrangement of CPU cores. Current flagship Android processors like the Exynos 2100 and Snapdragon 888 use three types of cores. The Snapdragon 888, for example, uses one Cortex X1 (high-power), three Cortex A78 (mid-power), and four Cortex A55 (low-power/high-efficiency) cores.
The Google Tensor is a 5nm eight-core design broken down into big, medium and small cores and uses two of the most powerful Cortex X1 cores clocked at 2.8 GHz, which should help the phone excel with some demanding tasks. In comparison, Qualcomm’s flagship Snapdragon 888 chip, which powers Samsung’s Galaxy S21 and many other high-end phones, only has a single X1 core.
On the other hand, the company also confirmed that rather than triple mid-tier cores, the Pixel 6 uses just two. They also aren’t the newer A78, but instead the older, less powerful, and less efficient A76 cores (running at 2.25 GHz) released way back in 2018.
The Pixel still uses four low-power A55 cores running at 1.8 GHz as well, while the GPU is the Mali G78MP20, which should offer gaming performance as good as any on Android device.
The use of the older A76 cores continues to be the biggest headscratcher, and Google didn’t reveal why it chose that road.
For its part, Google says the processor is 80pc faster than the Pixel 5; the GPU is 370pc faster. But considering the Pixel 5 was spec’d with a Snapdragon 765, that’s not saying too much, other than that the processor should be roughly competitive with existing flagship Android chips.
An ArsTechnica interview with Google engineers sheds some light on the core layout decisions.
Phil Carmack, VP of Google Silicon, explains:
“We focused a lot of our design effort on how the workload is allocated, how the energy is distributed across the chip, and how the processors come into play at various points in time. When a heavy workload comes in, Android tends to hit it hard, and that’s how we get responsiveness.”
He adds “when it’s a steady-state problem where, say, the CPU has a lighter load but it’s still modestly significant, you’ll have the dual X1s running, and at that performance level, that will be the most efficient.”
So there seems to be a greater bias towards having medium tasks run on the X1 cores, rather than the A76s when possible — hopefully leading to a more responsive phone. By dialing down the powerful cores more often “a workload that you normally would have done with dual A76s, maxed out, is now barely tapping the gas with dual X1s.”
As noted by ArsTechnica, having just one big core is actually a recent development for ARM-based chips. Traditionally, these chips have used two or more high-performance cores. Apple, for instance continues to stick with a simpler divide high-efficiency and high-performance cores.
“if you want responsiveness, the quickest way to get that, and the most efficient way to get high-performance, is probably two big cores,” Carmack noted while suggesting that having a single big core is only great for single-threaded benchmarks.
This means that Tensor is not an Apple-level leap in performance over competitors — at least when it comes to basic CPU and GPU tasks. Where the SoC shines is in AI and ML tasks with its new “TPU” or tensor processing unit (sometimes called a neural processing unit in other devices). There’s plenty of unexplored potential in this regard.
Unfortunately, Google was vague in the specs, other than showing off some tools enabled by Google Tensor, like HDR video at 4K 60 fps, the new Face Unblur feature, and the super-quick Live Translate implementation. The new SoC will allow the Pixel 6 to translate videos and messages quickly with its Live Translate feature, and it’ll be smarter about recognizing your voice as well. That should be particularly helpful when it comes to using your voice to type, edit and send messages. Most importantly, though, it’ll be able to do all of that work without consuming much battery life. Overall, the Tensor chip will perform around 80 percent faster than the Pixel 5, according to Google
Additionally, Google says Tensor also gives the Pixel 6 an extra layer of security. It’ll work together with the Titan M2 chip in the phone to protect against malware and other potential attacks
The company suggests it’s reluctant to share numbers because existing ML benchmarks are “backward-looking,” but basically wants us to know that Tensor is meant to run Google’s own ML algorithms optimally. The company says some of these machine learning tasks simply can’t run efficiently on other Android devices; I’m curious what Qualcomm has to say about that.
The Google Tensor SoC is an opportunity for Google to achieve the cohesion between hardware and software that Apple is best known for — to have great control over every part of the user experience.