Google's Tensor inside of Pixel 6, Pixel 6 Pro: A Look into Performance & Efficiency
by Andrei Frumusanu on November 2, 2021 8:00 AM EST- Posted in
- Mobile
- Smartphones
- SoCs
- Pixel 6
- Pixel 6 Pro
- Google Tensor
Conclusion & End Remarks
Google’s newest Pixel 6 and 6 Pro are definitely most interesting devices, as in many ways they represent Google most competitive and value-rich phones the company has been able to make in years. While today’s article isn’t focusing on the device itself – more on that in a later review, including more in-depth camera coverage, what we did have a deeper look today was at the new chip powering the phones, the new Google Tensor.
The company notes that the primary reason they saw the need to go with a customized silicon approach, was that current merchant silicon solutions didn’t allow for the performance and efficiency for machine learning tasks that the company was aiming for in their devices. This performance and efficiency is used to enable new use-cases and experiences, such as the many ML features we see shipped and demonstrated in the Pixel 6 series, such live transcribing, live translation, and image processing tricks, all that run on the Tensor’s TPU.
While Google doesn’t appear to want to talk about it, the chip very clearly has provenance as a collaboration between Google and Samsung, and has a large amount of its roots in Samsung Exynos SoC architectures. While yes, it’s a customised design based on Google’s blueprints, the foundation means that some of the defining characteristics of Exynos chips is still found on the Tensor, particularly power efficiency is one area of the SoCs that are very much alike in, and that also means that the Tensor falls behind, much like the Exynos, against Qualcomm’s Snapdragon solutions when it comes to battery life or efficiency.
Google’s CPU setup is a bit different than other SoCs out there – a 2+2+4 setup with X1 cores, A76 cores and A55 cores is unusual. The two X1 cores are fine, and generally they end up where we expected them, even if there’s a few quirks. The A76 cores, ever since we heard those rumours months ago that the chip would feature them, made no sense to us, and even with the chip in our hands now, they still don’t make any sense, as they clearly fall behind the competition in both performance and efficiency. Who knows what the design process looked like, but it’s just one aspect of the chip that doesn’t work well.
GPU performance of the Tensor seems also lacklustre – while it’s hard to pinpoint wrong-doings to the actual SoC here, Google’s choice of going with a giant GPU doesn’t end up with practical advantages in gaming, as the phones themselves have quite bad thermal solutions for the chip, not able to properly dissipate the heat from the chip to the full body of the phones. Maybe Google makes more use of the GPU for burst compute workloads, but so far those were hard to identify.
So that leads us back to the core aspect of the Tensor, the TPU. It’s the one area where the SoC does shine, and very clearly has large performance, and likely also efficiency advantages over the competition. The metrics here are extremely hard to quantify, and one does pose the question if the use-cases and features the Pixel 6 comes with were really impossible to achieve, on say a Snapdragon chip. At least natural language processing seems to be Google’s and the Tensor’s forte, where it does have an inarguably large lead.
One further aspect that isn’t discussed as much is not related to the performance of the chip, but rather the supply chain side of things. We of course have no idea what Google’s deal with Samsung looks like, however both new Pixel 6 phones are devices that seemingly are priced much more aggressively than anything we’ve seen before from the company. If this is related to the SoC bill of materials is just pure speculation, but it is a possibility in my mind.
In general, I do think Google has achieved its goals with the Tensor SoC. The one thing it promises to do, it does indeed do quite well, and while the other aspects of the chip aren’t fantastic, they’re not outright deal-breakers either. I still think energy efficiency and battery life are goals of highest priority in a design, and there we just absolutely need to see better improvements in the next generation Tensor. We don’t know what path Google is taking for future designs, but it’ll be interesting to see.
We’ll be following up with a more in-depth review of the actual Pixel 6 phones, starting with a camera-focused article – stay tuned.
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Alistair - Wednesday, November 3, 2021 - link
It's the opposite, the iPhone is massively ahead in performance, but every high end phone takes the same high end photos... you got the same photos but a lot less performance...aclos3 - Saturday, November 6, 2021 - link
I took some time to really test the camera and you are simply wrong. I have been photographing with it heavily for the last couple of days and the camera is incredible. Call it a gimmick or whatever, but the way they do their photo stacking puts this phone in a league of its own. If your main use case for a phone is benchmarking, I guess this is not your device.Lavkesh - Thursday, November 11, 2021 - link
Everyone and their grand mother do image stacking. iPhone is almost as good if not better even with a smaller sensor when compared to the latest Pixel. How's that for "in a league of its own"?Amandtec - Wednesday, November 3, 2021 - link
I don't doubt the veracity of your comment but I find the hostile undertone somewhat curious.damianrobertjones - Wednesday, November 3, 2021 - link
But... but... they said that it's amazing!! Who do I believe? /sZoolook - Saturday, November 6, 2021 - link
As long as they use Samsung process they will be hopelessly behind Apples Socs in efficiency unfortunately, would be interesting to see SD back on TSMC process for a direct comparison with Apple silicon.Tigran - Tuesday, November 2, 2021 - link
Performance looks very disappointing. Google promised 4.7x GPU performance improvement vs Pixel 5.singular9 - Tuesday, November 2, 2021 - link
I was enjoying how the speculation about the GS101 were claiming its "not far behind" the SD888. I was never expecting google to make another high end device, let alone one that undercuts most of the competition, as its just not what trends would say.I am not impressed. As someone who was rather hopeful that google would take control and bring us android users a true apple chip equivalent some day, this is definitely not the case with google silicon.
Considering how cookie cutter this design is, and how google made some major amateur decisions, I do not see google breaking away from the typical android SOC mold next generation.
Looking back at how long it took apple to design a near 100% solo design for the iPhone (A8X was the first A chip to use a complete inhouse GPU and etc design, other than ARM cores), that is a whopping 4 and a half years. Suppose this first google "designed" chip is following the same trend, an initial "brand name" break away yet still using a lot of help from other designs, and then slowly fixing one part at a time till its all fixed, while also improving what is already good, I could see google getting there by the Pixel X (10?). But as it stands, unless google dedicates a lot of time to actually altering Arm's own designs and simply having samsung make it, I don't see Tensor every surpassing qualcomm (unless samsung has some big breakthrough in their own CPU/GPU IP which may or may not come with AMD's help).
As the chip stands today, its "passable", but not impressive. Considering Google can get android to run really well on a SD765G, this isn't at all surprising. The TPU seems like a nice touch, since honestly, focusing on voice is more important than on "raw" cpu performance or something. I have always been frustrated with speech to text not being "perfect" and constantly having to correct it manually and "working around" its limitations. As for my own experience with the 6 Pro, its bloody good.
Now to specifics.
The X1 chips do get hot, as does the 5G modem. I switched the device to LTE for now. I do get 5G at home and pretty much most places I go, and it is fast, its not something I need right now. I even had a call drop over 5G because I walked around a buildings corner. Not fun.
The A76 excuse I have heard floating around, is that it takes up less physical die space, by A LOT. And apparently, there was simply no room for an A77 or A78 because the TPU and GPU took up so much room. I don't understand this compromise, when the GPU performance is this mediocre. Why not simply use the same GPU size as the S21 (Ex2100) and give the A78's more room? Don't know, but an odd choice for sure.
The A55 efficiency issues are noticeable. Try playing spotify over bluetooth for an hour, and watch the battery drain. I get consistently great standby time, and very good battery life when heavily using my device, but its these background screen off tasks that really chug the battery more than expected.
Over all though I haven't noticed any serious issues with my unit. The finger print scanner works as intended, and is better than my 8T. The camera does just as well if not better than the previous pixels. And over all...no complaints. But I wonder how much of this UX comes from google literally brute forcing their way with 2 X1 cores and a overkill GPU, and how much of it is them actually trying.
As for recommendations to google for Tensor V2, they need to not compromise efficiency for performance. This phone isn't designed to game, cut the GPU down, or heck, partner with AMD (who is working with samsung) to bring competitive graphics to mobile to compete with Adreno from QComm. 2 X1 cores, if necessary, can stay, but at that point, might as well just have 4 of them and get rid of all the other cores entirely and simply build a very good kernel to modulate the frequency. Or make it a 2+6 design with A57 cores. As someone who codes kernels for pixels and nexus devices for a long time, trying to optimize the software to really get efficiency out of the big.LITTLE system is near impossible, and in my opinion, worthless unless your entire scheduler is "screen on/off" based, which is literally BS. I doubt google has any idea how to build a good CPU governor nor scheduler to truly make this X+X+X system even work properly, since I have yet see qcomm or samsung do it "well" to call commendable.
The rest of the phone is fine. YoY improvements are always welcome, but I think the pixel 6/pro just really show how current mobile chips are so far behind apple that you might as well give up. YoY improvements have imo halted, and honestly no one seems to be having the thought that maybe we should cut power consumption in half WITHOUT increasing performance. I mean...the phones are fast enough.
Who knows. We will see next year.
PS: I also am curious what google will do with the Pixel 6A (if they make one at all). Will it use a cut down GS101 or will it get the whole chip? It would seem overkill to shove this into a 399$ phone. Wonder what cut downs will be made, or if there will be improvements as well.
sharath.naik - Tuesday, November 2, 2021 - link
Good thoughts, there is one big issue you missed. Pixel camera sensors 50mp/48mp being binned to 12mp yet Google labeled them as 50mp/48mp. Every shot outside the native 1x,4x is just a crop of the 12mp image including pottaitk3mp crop) and 10x(2.5mp crop}.teldar - Thursday, November 4, 2021 - link
You are absolutely a clueless troll and should go back to your cave. Your stupidity is unwanted.