Mesa 20.1 Sees Big Optimizations To Its Soft FP64 Implementation

[phoronix]

Phoronix: Mesa 20.1 Sees Big Optimizations To Its Soft FP64 Implementation

For the past year Mesa has offered a "soft" implementation of FP64 capabilities for GPUs lacking FP64 hardware capabilities in order to support ARB_gpu_shader_fp64 as required by OpenGL 4.0. Optimizations were merged today to significantly enhance the "soft FP64" capabilities of Mesa...

http://www.phoronix.com/scan.php?page=news_item&px=Mesa-20.1-Optimized-Soft-FP64

[darkbasic]

Will there be benchmark of this?

[Nille_kungen]

Will there be benchmark of this?

Is there any real application that use it to benchmark?

[Michael]

Is there any real application that use it to benchmark?

As well as any practical hardware in 2020 relying on it.

[G-P-L]

Loosely connecting to the topic, but I have a TeraScale3 (r600g) card which has FP64 hardware support (so don't need this software emulation) and thus practically supports OpenGL up to 4.5. With Mesa 20.0.1 the glxinfo only shows 4.3 (core) support in the case of this card and I also have GCN1 and GCN5 cards with OpenGL 4.6 capability and they only expose 4.5 support. Which is interesting, because the MesaMatrix is clearly showing OGL 4.5 and 4.6 support in the two cases. Do you have any idea what can be the problem? The distro is Arch Linux.

To the topic: I think when this software FP64 support implemented the older TeraScale1/2 GPUs also could in theory support OGL 4.5. For older games running under Wine this can be useful.

[smitty3268]

Loosely connecting to the topic, but I have a TeraScale3 (r600g) card which has FP64 hardware support (so don't need this software emulation) and thus practically supports OpenGL up to 4.5. With Mesa 20.0.1 the glxinfo only shows 4.3 (core) support in the case of this card and I also have GCN1 and GCN5 cards with OpenGL 4.6 capability and they only expose 4.5 support. Which is interesting, because the MesaMatrix is clearly showing OGL 4.5 and 4.6 support in the two cases. Do you have any idea what can be the problem? The distro is Arch Linux.

To the topic: I think when this software FP64 support implemented the older TeraScale1/2 GPUs also could in theory support OGL 4.5. For older games running under Wine this can be useful.

For the r600 card, I believe the driver is artificially limited to 4.3 because Khronos added validation/testing requirements for being able to support GL 4.4 and above.

By the time such support was added to the driver, AMD wasn't interested in getting it officially validated, and seemed to want to avoid claiming it was compatible without the tests.

However, the driver does support all the necessary functionality, so all you have to do is force the correct GL version via an environment variable and it should work.


For the GCN cards, is Mesa built with the NIR backend enabled by default? If it's using TGSI, that will limit it to 4.5. There should be another environment variable to force that, so you could see if that enables 4.6 for you.

[Guest]

As well as any practical hardware in 2020 relying on it.

Well I still have this old tablet PC with an AMD C-60 APU. Soft64FP implementation is relevant for that GPU. So yeah, I'm interested

[G-P-L]

For the r600 card, I believe the driver is artificially limited to 4.3 because Khronos added validation/testing requirements for being able to support GL 4.4 and above.

By the time such support was added to the driver, AMD wasn't interested in getting it officially validated, and seemed to want to avoid claiming it was compatible without the tests.

However, the driver does support all the necessary functionality, so all you have to do is force the correct GL version via an environment variable and it should work.


For the GCN cards, is Mesa built with the NIR backend enabled by default? If it's using TGSI, that will limit it to 4.5. There should be another environment variable to force that, so you could see if that enables 4.6 for you.

Thanks for your answer! You are right, I checked the supported OGL extensions which are needed to support a given OGL level and in both case (r600 and radeonsi) the extensions are there for 4.5/4.6, only the driver is not reporting the maximum supported level.

[Nille_kungen]

Loosely connecting to the topic, but I have a TeraScale3 (r600g) card which has FP64 hardware support (so don't need this software emulation) and thus practically supports OpenGL up to 4.5. With Mesa 20.0.1 the glxinfo only shows 4.3 (core) support in the case of this card and I also have GCN1 and GCN5 cards with OpenGL 4.6 capability and they only expose 4.5 support. Which is interesting, because the MesaMatrix is clearly showing OGL 4.5 and 4.6 support in the two cases. Do you have any idea what can be the problem? The distro is Arch Linux.

To the topic: I think when this software FP64 support implemented the older TeraScale1/2 GPUs also could in theory support OGL 4.5. For older games running under Wine this can be useful.

I don't have my NI hardware (hardware FP64) any more but as i can remember it Supported OpenGL4.5 when i checked glxinfo.
I now use RavenRidge and it shows as OpenGL 4.6
The softFP64 is already included as far as i understand so i don't think it will change anything like that.

Well I still have this old tablet PC with an AMD C-60 APU. Soft64FP implementation is relevant for that GPU. So yeah, I'm interested

You might need it for OpenGL 4.5 support but i don't think you will ever use it.
What application use FP64?