NVIDIA Resizable BAR Performance - A Big Boost For Some Linux Games

[phoronix]

Phoronix: NVIDIA Resizable BAR Performance - A Big Boost For Some Linux Games

Back in March NVIDIA announced they would be supporting the GeForce RTX 30 series with Resizable BAR support via a video BIOS update for supported systems. Recently I've been looking at the performance of a GeForce RTX 3080 once flashing the graphics card under Linux with Resizable BAR support and the performance is quite compelling for Vulkan-based games where this functionality is working.

https://www.phoronix.com/vr.php?view=30266

[schmidtbag]

Wow some of those are a real big difference. From what I recall, Nvidia's performance was roughly equal to Windows. Windows doesn't seem to get this big of a performance improvement, so, I wonder if this gives Linux+Nvidia an edge.

[spykes]

Is this only supported on high-end RTX 30XX cards ?
If not, I wonder if the gains are similar on my RTX 2070 Super.

[aufkrawall]

Wow some of those are a real big difference. From what I recall, Nvidia's performance was roughly equal to Windows.

If there is any performance difference, Nvidia Linux is slower than Nvidia Windows in games.

spykes Nvidia does not provide vbios updates with rBAR for anything older than Ampere.

[spykes]

spykes Nvidia does not provide vbios updates with rBAR for anything older than Ampere.

OK so it's pretty useless for most users. Thanks for the info.

[torsionbar28]

Don't forget to thank AMD for developing the Resizable BAR feature, presenting it to PCI-SIG, and getting it included as part of the PCIe 3.0 standard. Resizeable BAR wouldn't exist without AMD. Though motherboards supporting Resizeable BAR have been around for over a decade, I think the AMD RX 6000 series is the first GPU to actually use it. Good to see other GPU vendors finally supporting this feature as well.

[Mel Spektor]

I don't understand is BAR and ReBAR the same thing?? because lots of hardware review sites seem to be confusing the terms... Also if I understand correctly AMD SAM it's a different thing.

[Mel Spektor]

Don't forget to thank AMD for developing the Resizable BAR feature, presenting it to PCI-SIG, and getting it included as part of the PCIe 3.0 standard. Resizeable BAR wouldn't exist without AMD. Though motherboards supporting Resizeable BAR have been around for over a decade, I think the AMD RX 6000 series is the first GPU to actually use it. Good to see other GPU vendors finally supporting this feature as well.

what you are saying is that my B350 motherboard supports ReBAR? because according to AMD you need a b450 motherboard

[bridgman]

I don't understand is BAR and ReBAR the same thing?? because lots of hardware review sites seem to be confusing the terms... Also if I understand correctly AMD SAM it's a different thing.

BAR = Base Address Register, the set of PCIE config space registers which tells the SBIOS and OS how big the VRAM is and allows the SBIOS/OS to set the starting address (rather than having to set jumpers like the old days). VRAM BAR's usually default to 256MB.

Resizeable BAR = a PCIE facility that allows you to choose BAR size from one of a few different options.

SAM = marketing term for driver code that takes advantage of having a BAR that covers the entire VRAM and improves performance by doing fewer and/or faster copies.

[smitty3268]

I don't understand is BAR and ReBAR the same thing?? because lots of hardware review sites seem to be confusing the terms... Also if I understand correctly AMD SAM it's a different thing.

Bridgman is correct in defining what the terms actually mean, but I think it's worthwhile to add that if you ever see any of these terms in any hardware review site articles they are certainly all referring to the same thing. Just mixing up their terminology a bit.