For Radeon Gamers On Ubuntu 20.04 LTS, It's Generally Worthwhile Flipping On RADV's ACO

[Brisse]

I've been using ACO for everything for months, and besides an issue with Wolfenstein II: The New Colossus back in Mesa 19.3 (fixed in 20.0), I haven't run into any noticeable issues at all. It's been very solid and I suggest everyone should try to enable it system wide. In the rare case you run into a troublesome game, you can always set 'RADV_PERFTEST=llvm' for that particular game.

[oibaf]

Sorry I missed the point that he uses your repo. Thank you for reminding!
Btw is your repo still build against llvm9. I mean is the bug with llvm10 and opencl still existing? at the moment I'm building it against 10 but without opencl.

My repo still uses llvm9, 10 it's still broken, but there is a pending patch:

https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4511

When properly merged I'll build against llvm10.

[enlar]

Article needs a short explanation about what ACO is... ;-)

[randomsalad]

It's not just performance you gain, but also compatibility. A lot of very popular games will show severe visual artifacts when using the LLVM shader backend. In my experience, GTAV and Assassin's Creed Odyssey were two games that were giving me a lot of trouble with incorrect shading making the games unplayable in practice, but switching to ACO (the shader backend, not the game) made these problems go away.

[wizard69]

Article needs a short explanation about what ACO is... ;-)

Yeah, there is this assumption that ever acronym is well known in the Linux world. GPU driver technology is a bushel basket full of such acronyms. Even a link would do.

[TemplarGR]

It's not just performance you gain, but also compatibility. A lot of very popular games will show severe visual artifacts when using the LLVM shader backend. In my experience, GTAV and Assassin's Creed Odyssey were two games that were giving me a lot of trouble with incorrect shading making the games unplayable in practice, but switching to ACO (the shader backend, not the game) made these problems go away.

I wonder if ACO will be the solution for broken Ambient Occlusion on some games with the radeonsi driver. Mainly Unity games like Two Point Hospital and Parkitect have artifacts with Ambient Occlusion on. Yesterday i tried The Colonists and Ambient Occlusion makes the whole screen very dark, it gets fixed when disabled. For Two Point Hospital and Parkitect the fix is to disable DCC with "AMD_DEBUG=nodcc" (although obviously this would cost some performance). But i am not aware of how DCC is implemented. Perhaps it uses shaders in some capacity? Or perhaps the ambient occlusion shader has incompatibilities with DCC on radeonsi? This issue is not present on Windows with Adrenaline drivers.

In any case, can't wait for ACO to come to radeonSI.