Thursday, February 2nd 2023
Dead Space Performance Jumps 46% with Resizable BAR Enabled
The PCI Resizable BAR feature can have a major impact on the performance of "Dead Space" (the 2023 reboot). sxKYLE on Reddit discovered that his GeForce RTX 4080 "Ada" experienced a major performance jump from 76 FPS up to 111 FPS (+46%) with resizable BAR enabled. NVIDIA Profile Inspector was used to enable resizable BAR for the game. The feature allows the CPU to see the graphics card's video memory as a single, continuously-addressable block, rather than through 256 MB apertures. We can imagine how "Dead Space" in particular could benefit from the feature, as the game's campaign is a single continuous action sequence with assets being constantly streamed to the GPU (and no level load screens).
Source:
sxKYLE (Reddit)
35 Comments on Dead Space Performance Jumps 46% with Resizable BAR Enabled
I know W1zz told me one time that all modern systems have resize bar on by default, so this should be a null find.
But to increase performance by such a large percentage? There must be other driver optimisations added or bugs removed. This can't be just the rebar.
edit: nm just read @Assimilator post
ReBAR is a strict improvement in the PCIe protocol with absolutely zero tradeoffs. Any scenario that regresses performance with ReBAR-on can only be caused by a deficiency somewhere (game engine, GPU driver, or GPU architecture - more likely the latter two, especially for recent releases). Intel's Arc GPUs have an even bigger dependency on ReBAR because it's a new arch so they didn't bother to optimize the ReBAR-off case, and that's the right thing to do since every minimally current CPU/chipset/motherboard also supports ReBAR. I suspect RTX GPUs are the opposite, they probably still have drivers and maybe even memory controllers over-tuned for the ReBAR-off case, causing more regressions than any competing GPU if you turn it on for all games.
AMD and Intel are taking riskier approach, in order to compete on price to perf, at the cost of possible system instabilities that will turn away people who just want to play game and not tinkering with their system all the time.
Kinda funny that you think leaving out performance for the sake of stability is a problem
I can't wait for DirectStorage to come into play as well, it's about damn time.
Anyone?
It's a problem because they're leaving out performance and it's not any more stable. AMD has resizable bar working with no problems and Nvidia doesn't, which is why they whitelist everything by default, it's as simple as that.
Not saying that this claim is invalid, but these two screenshots aren't a good comparison
Don't have any data right now, finishing my rebench of all cards all games on 13900K
Hopefully there is a performance bump and more games make use of ReBar, but I will wait for proper testing before buying the %.
NVIDIA Inspector is an invaluable tool.
Having to disable a feature by default but then you still get both instability and potentially lost performance is "no good reason" in my book, they should just get on it with it and fix it. Slow memory transfers are causing more stalls in the rendering pipeline, the lower power usage is exactly what you'd expect.
Do you even think about what you type? AMD and intel blacklist software that suffers from ReBar, so clearly it has some tradeoffs and compatibility issues.