segunda-feira, 19 de janeiro de 2015

CES 2015: Nvidia Announces the Tegra X1 Processor

During this year's Consumer Electronics Show (CES), Nvidia has given us a glimpse of their next generation mobile processor. And it's fantastic. For the first time implementing Nvidia's new mobile first strategy, they were able to quickly port their latest graphics architecture on to their Tegra line. As a result, the new Tegra X1 processor has a GPU based on Nvidia's brand new architecture, dubbed Maxwell. Thanks to its advanced power efficiency, Nvidia was able to build a very, very powerful GPU for the Tegra X1 without exceeding the power budgets that define the ultra-mobile market. The Tegra X1 will be most likely destined for high-performance and gaming tablets, and maybe even high-end Chromebooks.


The truth is that 28nm is getting old. This generation, we're starting to see manufacturers moving to the smaller 20nm process node. Apple has done it with its A8 and A8X SoCs, and Samsung has done it with its Exynos 5433 processor. Nvidia has also now jumped on the 20nm wagon with the Tegra X1. Built by TSMC, the Tegra X1 is Nvidia's first SoC to benefit from a 20nm process node, and that should really help to keep the power consumption in check, which is necessary for Nvidia, especially considering the extremely beefy GPU.


Unlike with the Tegra K1, which had a 32-bit Cortex-A15 version and a 64-bit Denver version announced, for the Tegra X1 Nvidia has so far only mentioned one version, which ditches their own Denver core in favor of complete ARM-designed cores. It's still 64-bit, luckily. The Tegra X1 features a big.LITTLE CPU configuration, with four high-performance Cortex-A57 cores, and four Cortex-A53 cores designed for low-power operation. At this point, clock speeds are not specified, however. It must be pointed out that, unlike with Samsung's Exynos 5433, which also uses big.LITTLE quad-core Cortex-A57s and A53s, the Tegra X1's CPU cannot use both CPU clusters at the same time, so it can't be considered an actual octa-core CPU. Which is a good choice by Nvidia, considering that the Cortex-A57 is already a very powerful core, and considering how most applications don't scale well beyond four cores. At this point, performance estimates cannot be made due to the unannounced clock speeds, but given that the Tegra X1 is meant for high-end tablets, I imagine that the clocks will be pretty high, and it's pretty safe to say that the Tegra X1 will be no slouch when it comes to CPU performance.

Of course, another variant of the Tegra X1 with a Denver CPU is definitely very possible, but like with the Tegra K1, such a variant would only be released later into the year. In truth, I'm surprised that Nvidia didn't make Denver the default CPU configuration for Tegra X1. It showed very good performance in the Nexus 9, and I would like to have seen the Tegra X1 launch with it.


This is, of course, the spotlight of Nvidia's announcement. Nvidia's mobile first development strategy has enabled them to adapt their latest GPU architecture for mobile very quickly, and that will represent a huge advantage for Nvidia over the competition. With a 2x performance/watt advantage compared to Kepler, the new Maxwell architecture is extremely power efficient, delivering much more performance than Kepler, without using any more power.

For the Tegra K1, Nvidia had a single Kepler SMX (192 CUDA cores) running at up to 950MHz (although the devices that launched with it usually kept the clock speed at 850MHz). A single SMX had four ROPs (Render Output units) and 8 TMUs (Texture Mapping Units). However, with the Tegra X1, Nvidia is moving to two of Maxwell's basic graphics units, named SMM. Each contains 128 CUDA cores, therefore, the Tegra X1 has a total of 256 CUDA cores. These are accompanied by 16 ROPs and 16 TMUs, all this at, according to Nvidia, a max clock speed of 1GHz. This clockspeed sounds even a bit preposterous, and it is very possible that tablets running on Tegra X1 will keep the GPU clock at a bit less than that, for thermal and power budget purposes.

Wrapping up the technical stuff, here's a table comparing Nvidia's last few SoCs:

Tegra X1 Tegra K1 Tegra 4 Tegra 3
 CPU   64-bit Quad-core Cortex-A57 + Quad-core Cortex-A53   32-bit Quad-core Cortex-A15 @ 2.3GHz + Single "companion" Cortex-A15 core  or 64-bit Dual-core Denver @ 2.5GHz  32-bit Quad-core Cortex-A15 @ 1.9GHz + Single "companion" Cortex-A15 core @ ~800MHz  Quad-core Cortex-A9 @ 1.6GHz + Single "companion" core @ ~500MHz
 Lithography   20nm  28nm  28nm  40nm
 GPU core configuration   256 CUDA cores
 16 ROPs
 16 TMUs
 192 CUDA cores
 4 ROPs
 8 TMUs
 48 Pixel shaders
 24 Vertex shaders
 8 Pixel shaders
 4 Vertex shaders
 GPU clock  1,000MHz  950MHz  672MHz  520MHz
 FP32 Peak Compute power (GFLOPS)  512  365  97  12.5
 Pixel Fill Rate (MP/s)  16,000  3,800  ?  ?
 Texture Fill Rate (MT/s)  16,000  7,600  ?  ?
 Memory Interface   Dual-channel 64-bit LPDDR4-1600 (25.6GB/s)  Dual-channel 64-bit LPDDR3-1066 (17GB/s)  Dual-channel 32-bit LPDDR3-1866 (15GB/s)  Single channel 32-bit LPDDR3-1600 (6.4GB/s)

The table clearly shows how far Nvidia has come since the Tegra 3. The Tegra X1 is a huge leap forward compared to the K1, in every aspect, especially in the graphics department. The Tegra X1's GPU is far beyond what previous-gen consoles like the Xbox 360 and PS3 could achieve, and even some current low-end dedicated laptop GPUs are less powerful than the Tegra X1's GPU. Kudos to Nvidia for this impressive achievement.


Nvidia's new focus on bringing their latest GPU architectures to mobile is doing them a lot of good. The new Tegra X1 has a very, very large graphics processor, but with the benefit of the Maxwell architecture's astounding power efficiency.

In general, Nvidia's new processor is a great package overall, showing off excellent specs and top notch future proofing. Everything that's necessary for a new high-end SoC is there: 64-bit processing, 20nm process, for instance. While in most aspects Nvidia is playing in equal ground with other flagship mobile processors, its GPU sets it apart from anything else on the market now. The Tegra K1 was already ahead of pretty much every other SoC, except for the Apple A8X, in graphics benchmarks. Now the Tegra X1 will help Nvidia extend their lead even further. I was only a bit disappointed that Nvidia, at least for now, is not making use of its Denver CPU cores for the Tegra X1 (and considering how well they performed in the Nexus 9, one might wonder why Nvidia made this decision).

In terms of actual products that might eventually carry the Tegra X1, I believe that smartphones are still out of the picture. Despite the 20nm process and Maxwell's efficiency, a 256-core GPU might still be too much for a smartphone's battery size and thermal dissipation capacity. However, I can speculate that maybe a Tegra X1 with a much lower clocked GPU could make its way into a high-end phablet. 

Overall a great package, with the added benefit of a GPU that rivals even some lower-end dedicated laptop GPUs. Nvidia did a great job with its new SoC, and while it may still not be fit for smartphones, the Tegra X1 is just perfect for high-end tablets and any form of compact gaming devices, and might just turn out to be this year's most powerful SoC. 

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