this post was submitted on 26 Oct 2023
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Linux Gaming

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[–] sugar_in_your_tea@sh.itjust.works 15 points 1 year ago (1 children)

"works fine" is very different than "is equivalently optimized."

Valve has done a lot of work to get games to work well on the Steam Deck, and that likely translates to other AMD GPUs. So it makes total sense that Valve would optimize the Proton translation layer for DirectX calls to the AMD driver differently than the NVIDIA driver (or rather, in a way that AMD handles better). A big issue in GPU optimization is keeping it busy, so perhaps the AMD driver working with Valve's patches on the DirectX to Vulkan layer improve utilize m utilization. That could translate to a modest performance improvement even on well optimized games (perhaps 5-10%, probably not more than 20%).

I don't know if that's what's going on here, but it's a plausible explanation.

[–] havokdj@lemmy.world -4 points 1 year ago (2 children)

I can see why you'd think that, but what you fail to understand is that valve is not the only one working on proton, and valve themselves did not even make DXVK. Those are free and open source efforts and valve even pays external devs to commit to that software. I'm telling you that DXVK itself is not going to give a boost to graphical performance because it literally cannot, those are extra instructions that your GPU has to perform in order to send out frames.

Directx to vulkan translation is exactly that, translation. It receives directx calls and translates them to vulkan. For one, it has overhead, two, if the game is optimized, it is already going to be running at max performance on windows, using DXVK is going to slow the GPU time down because it will have to perform more calculations. No scheduler will save you from that, not even the Linux one, because it isn't something that is handled by the scheduler.

[–] sugar_in_your_tea@sh.itjust.works 6 points 1 year ago* (last edited 1 year ago) (1 children)

Two things:

  • I never said Valve built DXVK or even WINE, just that they have a vested interest to ensure it works well on their AMD-based hardware
  • I never mentioned anything about the scheduler or any Linux imtrinsics other than the AMD GPU kernel module

DirectX -> Vulkan isn't a direct translation since the APIs aren't 1:1, so there's going to be some tuning in how APIs are mapped, and the tuning can differ depending on the GPU driver you're using.

It's the same with processors, you can optimize a compiler to work better on AMD vs Intel or vice versa (look at Intel C++ compiler benchmarks for an example of that), even if they use the exact same set of instructions because the microarchitectures are optimized differently. This is because the way the instruction set gets mapped to the microarchitecture can impact performance significantly (something like 10% is possible, depending on the benchmark).

GPU drivers are complicated, and there are a lot of areas where the interaction between the driver, software, and system services can be optimized. AMD's drivers are open source, which helps with those optimization efforts. Then you throw in a big, well-funded, and motivated company like Valve funding development (both through salaries and donations) and you end up with AMD GPUs getting extra attention for things like DXVK.

So I would expect AMD on Linux to perform better vs NVIDIA on Linux when compared to AMD vs NVIDIA on Windows. As in, the performance difference on Linux vs Windows would be more favorable for AMD cards than NVIDIA ones because AMD on Linux gets more attention than NVIDIA on Linux. I don't expect the same for compute, since NVIDIA invests heavily in that space on Linux, so it's not an inherent advantage of the platform (e.g. the scheduler discussion), but a question of where optimization efforts are focused.