Resizable BAR (Smart Access Memory) Now Available on Nvidia RTX 3000 Series GPUs

[RejZoR]

And as expected, after turning ReBAR off, Borderlands 3 became butter smooth again. Framerate might be slightly lower as whole, but at least I don't get absolutely absurd lagging, stuttering and straight up pauses weirdness that almost drove me insane.

 

Now I wonder if Radeon RX6000 cards are experiencing the same issue or it's a GeForce only thing... Especially since Borderlands 3 is AMD's love affair...

[StDragon]

3 hours ago, RejZoR said:

And as expected, after turning ReBAR off, Borderlands 3 became butter smooth again. Framerate might be slightly lower as whole, but at least I don't get absolutely absurd lagging, stuttering and straight up pauses weirdness that almost drove me insane.

 

Now I wonder if Radeon RX6000 cards are experiencing the same issue or it's a GeForce only thing... Especially since Borderlands 3 is AMD's love affair...

In theory, there should be no adverse effects with ReBAR enabled. Probably a bug with the driver as I doubt the game engine would need to be optimized for this feature.

[RejZoR]

18 minutes ago, StDragon said:

In theory, there should be no adverse effects with ReBAR enabled. Probably a bug with the driver as I doubt the game engine would need to be optimized for this feature.

Yeah, it's really weird. It does feel faster with it, but it's a jittery stuttering mess. Even things like flipping through guns in vending machines feels like they are stuttering.

[porina]

https://www.techpowerup.com/review/nvidia-pci-express-resizable-bar-performance-test/

 

TechPowerUp have tested it on/off. In short, there's the expected low single digit % improvement on average for the titles that benefit from it, and no difference for the non-whitelisted titles. 

[RejZoR]

It didn't occur to me, but ReShade might be the reason for my problems. Tough I don't know how, but I guess it's possible. I'll remove it and see how it goes.

[hollyh88]

nice cant wait to enable this for my 2070 super

 

oh no i forgot they dont care about the consumer so why make us happy with free performance for cards we do have  

[Laborant]

Apparently, someone uploaded the "vulkaninfo"-output to Sascha Willem's Website of GPU-Vulkan-Support... and I am super confused.

 

Without sizeable BAR, as expected (and only available since Vulkan 1.2), a RTX 3080 reports on vulkaninfo: 214MB of device-local, host-visible and the rest of its memory being device-local (without being host-visible). (The 3rd reported heap is the normal CPU-RAM)
It's about the same on a Radeon RX 6800 XT (but there, the full "memory mapped"-BAR of 256MB is host visible - Nvidia seems to need some of that area for driver-internals)

When activating ReBAR (or SAM as AMD names it) on a RX 6800 XT, the full 16 GB are reported being "host-visible" as one would expect. AMD just opens up its device memory to the host. How ReBAR is intended...

 

Now, the confusing part: When activating ReBAR on an RTX 3080, MORE than the available 10GB is reported as "device local and host visible". Coincidentally, it matches the CPU-RAM size...?

 

NVIDIA GeForce RTX 3080 - Vulkan Hardware Database by Sascha Willems (gpuinfo.org) (without ReBAR) (3 heaps, as intended)
NVIDIA GeForce RTX 3080 - Vulkan Hardware Database by Sascha Willems (gpuinfo.org) (with ReBAR - GPU reports more than 10GB of Memory being "device-local") (3 heaps: 1 CPU, 1 GPU (host visible, waaay too big) and 1 GPU (not host-visible WHY?!)

AMD Radeon RX 6800 XT - Vulkan Hardware Database by Sascha Willems (gpuinfo.org) (without ReBAR/SAM) (3 heaps: 1 CPU, 1 GPU[host-visible] 1 GPU [not host-visible])
AMD Radeon RX 6800 XT - Vulkan Hardware Database by Sascha Willems (gpuinfo.org) (with ReBAR/SAM) (2 heaps: 1 CPU, 1 GPU [host-visible])

Has anyone a clue why this might be the case? I just see a possible segfault from this. My own 3080 (ordered on launch-day) did not arrive yet. So I cannot just write a program that fills up that advertised memory and look what happens. (And my trusty Vega 64 does not support it...)
From this chaos, I kinda see why Nvidia "whitelists" games... 

I expect them to still "lock down" the "open BAR memory mapping" thing, as they historically limited access to that area to Quadro and Tesla cards. 

[RejZoR]

Interesting, Borderlands 3 runs significantly better with ASUS's RAMCache III installed. Basically it's RAM caching software to speed up SSD/HDD access. Showing Borderlands 3 really does seem to do some weird stuff with storage subsystem for it to run like turd when ReBar is enabled.

[StDragon]

10 hours ago, RejZoR said:

Interesting, Borderlands 3 runs significantly better with ASUS's RAMCache III installed.

Why not PrimoCache?

[RejZoR]

9 hours ago, StDragon said:

Why not PrimoCache?

I don't have the license at the moment as I gave it away to my cousin for the hybrid storage I set him up with. I do have RAMCache as I got it with my new mobo. It essentially does the same thing with less controls to fiddle with.