Mesa 11.1-dev Tests With The Reverted RadeonSI Performance

[mao_dze_dun]

Ok, so I have a question. Since it seems not all of the GPU companies are turning to open source drivers on Linux - how are they going to solve the multi-GPU problem. So far Crossfire/SLI has not actually worked in Linux and in Windows they use profiles - a solution that is hardly elegant or efficient. Will Vulkan (and DX12 on Win) remove the need for such profiles being closer to the metal?

[schmidtbag]

Ok, so I have a question. Since it seems not all of the GPU companies are turning to open source drivers on Linux - how are they going to solve the multi-GPU problem. So far Crossfire/SLI has not actually worked in Linux and in Windows they use profiles - a solution that is hardly elegant or efficient. Will Vulkan (and DX12 on Win) remove the need for such profiles being closer to the metal?

To my knowledge, this is an extremely low priority. I wouldn't be surprised if Vulkan is developed before multi-GPU, and about a half year ago I given up waiting for it and just simply bought a new more powerful GPU.
However...
IIRC, the interesting thing about mesa is it should be able to do a multi-GPU processing with any combination of GPUs, even across brands. If the hardware is too different, I can't imagine this would result in a good experience, but it's nice to know that you could (in theory) just slap in a bunch of old GPUs along with an IGP and play more detailed games.

[duby229]

That's one of the features of the loader on Vulkan. I've read that all the capability is there in mesa now, it just needs somebody to implement it. Don't know how hard or easy that would be though.

[smitty3268]

Ok, so I have a question. Since it seems not all of the GPU companies are turning to open source drivers on Linux - how are they going to solve the multi-GPU problem. So far Crossfire/SLI has not actually worked in Linux and in Windows they use profiles - a solution that is hardly elegant or efficient. Will Vulkan (and DX12 on Win) remove the need for such profiles being closer to the metal?

Vulkan exposes multi-GPU setups to the application, so that the engine in your game can figure out how to best use them. So yes, that will hopefully mean things like building CF/SLI support into the drivers and profiles will be less important.

That said, I think AMD has basically said they don't care at all about CF on their OSS drivers, Intel doesn't have multiple GPUs, and NVidia doesn't support the OSS drivers. So I don't think you're going to see much official work from anyone on that topic beyond implementing Vulkan, unless it comes from another OSS contributor that just feels like trying to implement it.

[bridgman]

Not so much "don't care at all" as "lower priority than a bunch of other stuff like stability, GL level support and single GPU performance".

It's pretty much a "pure software" exercise, mostly up in the common Mesa code not down in the HW-specific drivers, and if someone wants to work on it they should pretty much be able to solve it for all open source drivers at the same time.

[smitty3268]

Not so much "don't care at all" as "lower priority than a bunch of other stuff like stability, GL level support and single GPU performance".

I took the liberty of translating "we probably won't get to it for the next 5 years because we're busy on other more important stuff" as basically "we don't care about this feature in OSS drivers".

And AMD is right not too, in my opinion.

[bridgman]

Yeah, that's not unreasonable. I like my wording better because it adapts to unanticipated changes (more budget than planned, more progress than expected) better, but for the moment there's not much difference

[dungeon]

Ok, so I have a question. Since it seems not all of the GPU companies are turning to open source drivers on Linux - how are they going to solve the multi-GPU problem.

In a month we can only celabrate 10 years of CrossFire, i will drink few multi-beers and that is about it

[Raven3x7]

Thanks for the updated test

[mao_dze_dun]

Guess, I'll keep gaming in Windows for the next two years at least...