AMD Zen 2 + Radeon RX 5700 Series For Linux Expectations

AMD Radeon RX 5700 Series

The other half of AMD's E3 event was obviously focused on Navi/RDNA with the new Radeon RX 5700 series. RDNA is quite exciting from the hardware side with delivering 1.25x perf-per-clock and 1.5x perf-per-Watt over Vega. If all goes well on Linux, the new Radeon RX 5700 should compete with the GeForce RTX 2060 with its 36 compute units, 2304 stream processors, 8GB of GDDR6 video memory, and 7.95 TFLOPS compute power. Unfortunately pricing wasn't shared in advanced after various details leaked out on the first information of the event, but when you're reading this, the price should be announced (and via @phoronix is tweeting the event).

The Radeon RX 5700XT meanwhile competes with the GeForce RTX 2070 with its 40 compute units, 2560 stream processors, 8GB GDDR6, 9.75 TFLOPS, and higher clock speeds. Both the Radeon RX 5700 and 5700XT are launching on 7 July and will be tested on launch-day under Linux at Phoronix.

The new RDNA architecture rolls out a new compute unit design, multi-level cache hierarchy, a streamlined graphics pipeline, and display changes. The new compute unit is designed for 2x instruction rate by doubling of the scalar units and schedulers. There is also a single-cycle issue for the compute unit via Wave32 on SIMD32. Two adjacent compute unites can also be combined as a larger workgroup for resource pooling.

RDNA brings the new Radeon Display Engine that supports "DCC everywhere" for delta color compression in order to drive increasing resolution displays at higher refresh rates, such as 4K at 144Hz. There is also the new Radeon Media Engine offering VP9 4K60 decode, H.264 4K150/8K30 decode / 4K90 encode, and H264 4K60 decode / 4K90 encode.

One interesting remark shared during the event is that AMD will continue optimizing and using GCN for future, large GPUs. In particular, AMD is still expected to release new Vega products for the HPC market as it still holds its ground well in areas of compute in large GPUs.

Also announced during the event was Fidelity FX as a new open-source project under the GPUOpen umbrella. Fidelity FX will serve as an open-source image quality toolkit for game developers and we look forward to see its adoption. The code should be up on GitHub soon.

Linux Support For Radeon RX 5700 Series Is (Somewhat) A Mystery For Now But Hopeful

While I am quite confident in Linux on the new Ryzen 3000 series processors and am certainly excited about the Radeon RX 5700 series, I do have some reservations about the Linux support for Navi/RDNA simply with not having tested it myself yet, not seeing any demo boxes running Linux, and not having anyone on-site to talk about the Linux support in real depth. In particular, the open-source driver code for Navi has yet to be published that will offer the first glimpse if there is any missing bits of functionality for launch day, but it does look like that inaugural code drop will take place very soon.

AMD provided great launch-day support for Vega 20 but that wasn't a brand new architecture and overall their track record has greatly improved in recent years. With the new Radeon Media Engine and Radeon Display Engine I also have concerns given media/display issues with their Linux driver in the past and many nightmares still over the long drag out with DAL/DC code and not seeing display features in the mainline kernel like FreeSync until earlier this year. The Vega and Polaris support is in great shape and I am optimistic they have all the Navi support in order, but for now I'd simply "stay tuned" if thinking of buying Navi on launch day. As soon as that code drop happens or I get relayed concrete information on the Linux driver support, I'll certainly mention it on Phoronix as well as begin studying it. On launch day I'll certainly be able to offer a full analysis of the support and performance.

As for the mainline kernel support, we know that it won't be there for launch day but isn't going to be in stable/released versions of the Linux kernel and Mesa until September. AMD is aiming to get the RDNA/Navi support into the mainline Git code next month with the Linux 5.3 kernel, assuming the code indeed makes it out in time for review and staging in DRM-Next. Likewise, we're waiting to see the RadeonSI Gallium3D support for Mesa 19.2.

The Navi/GFX10 patches to the LLVM AMDGPU compiler back-end already started emerging and that will hopefully be in a good state for the LLVM 9.0 release in September. Meanwhile we should see the AMDVLK open-source Vulkan driver support for launch-day but the Mesa RADV Vulkan driver support remains a mystery unless the Google/RedHat/Valve developers leading that independent Vulkan driver managed to get their hands on RX 5700 series hardware early. Otherwise I'd suspect that to take at least weeks to see the support ironed out for this more common Radeon Vulkan driver that is popular with Linux gamers. For there to have been good support in stable Linux components by launch day, they would have needed to get the code out a month or two ago, albeit legal/internal reviews took longer than anticipated.

But for launch-day they will certainly be releasing a new Radeon Software for Linux (AMDGPU-PRO) driver package for those wanting to use their hybrid driver or all-open components. This works as an easy way to get the new graphics cards lighting up on Linux, but as many of you know, Radeon Software for Linux is primarily supported by a few enterprise Linux distributions. It's more difficult getting Radeon Software for Linux working on non-enterprise Linux distributions and even non-LTS Ubuntu releases.

So AMD will have Linux support for the Radeon RX 5700 series out at launch, but unless you are running the likes of Ubuntu 18.04 LTS with the packaged driver, there will at least be some hoops to jump through particularly if preferring the open-source/mainline driver stack. It's a pity not mainlined by launch day, but at least the source will be there at launch and this is much better than years ago when there wasn't code at launch day, when Vega display support was held up by the DAL/DC mainlining, and other past challenges.

AMD's open-source efforts continue moving in the right direction, just not as fast/punctual as we would hope; Navi could very well be their best open-source GPU support at launch for a major new architecture, but simply with not having tested the driver or even seen the code yet or seen any demo Linux system, for now I just have to say wait until the launch-day Linux review. I'll be testing the cards around the clock and trying all driver options with much excitement and hoping the support is all in good shape without any glaring issues. Keep in mind this is primarily a matter for those planning to upgrade at launch day or shortly thereafter; I have full confidence that at least by the time of the autumn Linux distribution updates there will be reasonably good Navi support available that is easily attainable to the Linux masses not wanting/able to use the packaged driver nor jumping through building their own code / third-party packages or other obstacles.

That's my brief overview of the products for now (keeping in mind there are many other sites covering the same information for those wanting a deep dive into the architecture, etc) while at Phoronix we are focusing on the Linux aspect of support and performance for where we provide our value. Stay tuned for 7 July as what will hopefully turn out to be a great launch for AMD's new products on Linux.