Unsolved Anomalous performance on VR

[gankailer]

Hi all, I have noticed the following observations on CPU/GPU fps (FPS, SIM, REN) while on the Benchmark TE in KTO (I am using VR), with Object Detail set to (2) and supersampling set to (1.1):

With parallel render thread OFF (i.e., set to 0), I get this performance:
FPS: 30
SIM: 30
REN: 38

It is obvious that this is a CPU bottleneck, as my total FPS is reduced to match that of the SIM FPS.

But when I turn parallel render thread ON (i.e., set to 1), I get this performance:
FPS: 18
SIM: 70
REN: 18

It now looks like a GPU bottleneck. I am struggling to find out why this is the case, considering that the parallel render thread should not harm my GPU fps by that much.

My specs and additional settings are as follows:
Meta Quest Pro
Ryzen 5800x
GeForce RTX 3080 10gb
32 gb DDR4 3200mhz RAM

Is there any possible explanation as to why the REN FPS drops by so much when turning off parallel rendering thread, and how this may be rectified? If I get a better CPU, e.g., a 5800X3D, will this issue be mitigated?

Thank you!

[airtex2019]

@gankailer I don’t know the entire answer, but I believe some assumptions are wrong…

The “REN” timing is not a measurement of your GPU load … it’s still CPU. It’s the background thread that serializes all the Draw() calls and issues the Present() call to handoff the frame to the GPU.

(My mental model: think of it as a three-stage assembly line … the “SIM” SimLoop thread does all the physics and input/network/AI handling etc for frame N, while the “REN” thread does the drawing for the previous frame N-1. Meanwhile the GPU is busy filling all the polygons for frame N-2.)

Measuring GPU load is a little tricky… even Windows taskmgr gets it hugely wrong, as observed in a recent thread.

Best measuring tool I know is NVidia FrameView… record and monitor the MsRenderPresentLatency field (clock time required to complete each frame, after handoff from Present() call). Or just monitor the GpuUtil field for a quick glance at whether you’re near 100 or not.

[Seifer]

You HW is definitely capable of more. Something is wrong there. Can you turn off the companion window and see if it helps?

set g_bVRNoPresent 1.

thanks

[gankailer]

@Seifer that field has been set to 0 already, and I’ve also done the same for environment mapping and water environment mapping, but have yet to turn off shadows. Any idea where else I can improve it?

[Seifer]

@gankailer you mean it is set to 1, right?

[SoBad]

@gankailer said in Anomalous performance on VR:

@Seifer that field has been set to 0 already, and I’ve also done the same for environment mapping and water environment mapping, but have yet to turn off shadows. Any idea where else I can improve it?

Turn off shadows and pretend it’s an overcast day.

[1508AD]

Turning off shadows is mandatory and i have close to the same Specs (5600x,3080) and im only using a Rift S (so rendering at a lot lower resolution)

[gankailer]

@Seifer yes, I meant that I set it to 1. Oops!

[gankailer]

@SoBad @1508AD oh man I’m not sure I could deal with the shadowless cockpit though Really waiting on BMS to release 4.38 now so the graphics will be on par at least with DCS

[Ricky]

@1508AD Thanks so much for confirming this. The shadows have a big impact on my frame rate as well, especially inside the cockpit. I’ve been wondering whether there was something wrong with my setup, but now I’m pretty sure I should just be flying instead of endlessly tweaking. Hopefully performance will slowly improve over the next updates. We can be patient!