Oculus Rift CV-1 frame drop and bad GPU usage

Good morning,

i recently encountered the following situation.

1. Start the game with headset on the table
   
2. Enable frame counter with hotkey
   
3. Move Rift with hands and observe fps (in my case 370fps with 100%GPU)
   
4. Cover proximity sensor in the Rift to make it enable screens (fps should drop to 90. GPU should drop from 100% to lower value ~45%)
   
5. Value of 90fps stays from then and GPU isn’t utilized fully (~75%) in the game. Oculus HUD shows huge number of frame drops and 0 or negative performance headroom. Means even with not being utilized fully the card is at its performance boundary.
   

Frame time after drop is around 22ms. In the game the fps drop even more to 45-22 depending on the scenery and amount of AI units. In this scenario the frames are in this range no matter if settings are on low with PD 1.0 or max with PD 2.0. just above 2.0 the fps drop further.

Specs

Z270E Mainboard

7700K CPU at 4.6Ghz

RTX 2080ti

32GB RAM

M.2 970Pro HDD

Concerning MSI Afterburner no sensor shows any sign of too much load or too much heat. The statement fans run in speed similar to idle. Before the drop the GPU and CPU fans run on load speed. Neither CPU nor GPU are maxed out. Both run almost col with load between 50-75% in peaks.

Greetings

Chris

Just as an addition

VRMark Orange Room Test gave me full points for VR.

Unigine Valley Benchmark at 1920x1200 full screen maxed setting gave peak fps of 278 and min fps of 35.

Similar Spec system and seen similar results too only my card is a RTX 2018 OC edition. My CPU i7 8700 @ 3.7GHZ / 32GB RAM DDR 4 Rog Striz Z370 / M.2 Drive

Got i5-4690 + 24GB + RTX 2060 Super + SSD

Same here

Before update 30-25fps

Now I get to 5Fps very unplayable

i7-9700k + 32 GB + RTX 2080 + SSD + Rift S

Same here. Before last 2 patches FPS stables at 45 FPS PD1.7 Mirrors ON.

Now, 30 FPS. Same video settings.

As there hasn’t been any reaction recently i use the vacation time to give this threat a push back to the top.

I hope that there will be a solution before Vulkan

Specs are Rift S and 7700K@4.8Ghz

Additional information: With the Rift CV1 the frametime was 1/90 + a little fraction of a ms. means 11.2-11.3ms so always a bot of loss. Now with the Rift S it’s 12.5ms + the same fraction. means 12.6-12.7ms.

It’s seems that something inside the program is relatively capping the performance. Single player with lowest PD and Settings is 67-80fps in Tomcat free flight. In an instant mission in Caucasus with the Tomcat the fps drop to 20. That’s a horrible bad performance.

I freeze now all my plans for buying even modules which are well enough feature vise till this is substantially changed.

Yes but as explained the sync is one aspect. The low utilization of the GPU and CPU shows something is going wrong. In screen (no VR) mode there is much more used and benchmarks show that at full utilization the system i have can generate 250fps at much higher quality settings and at the resolution of the Rift S.

In 5K the fps drop to 90 which would still be enough to drive moste available HMDs.

I concur from 30-40 hours in testing each setting and doing A LOT to try to get to the bottom of it, it's something holding off from DCS side, not Oculus. I'm happy to get on a call with someone and run through why I think this.

Bignewys settings improved the frame rate in instant action by a factor of 50%

It seems shadows of terrain objects have the most impact here.

https://forums.eagle.ru/album.php?albumid=1799

With the Rift CV1 the frametime was 1/90 + a little fraction of a ms. means 11.2-11.3ms so always a bot of loss. Now with the Rift S it’s 12.5ms + the same fraction. means 12.6-12.7ms.

those numbers look correct.

rift cv1 is 90hz refresh ->. 11.1ms

rift s is 80hz refresh ->. 12.5ms

you can’t change that. it’s part of the headset design

We will see. The problem is not the math but that no matter what happens the frametime is slightly above the expected. As we see something in the Headset the GPU must deliver frames. So there are frame in the correct frametime window. As the average shown in the Performance overlay of DCS (FPS) suggests, frametime is slightly above the needed to be accepted by the Oculus runtime. By this the and the fact that the GPU is fully utilized before the Rift is activated, indicates sort of side effect or a bug. I am in contact with Oculus and submitted them my logs to give them chance to check.

At the moment i have the impression that everything is sort of in a stall until Valkan comes out. Maybe because devs see no need to improve it before the magic is delivered by a new graphics engine. To be honest I see this as a bad decision because it could be that Vulkan by itself won’t deliver the expected improvements in the first iteration. So basically we see what today’s hardware is able to deliver (VRMark Benchmark results). The legacy code of the old engine is for sure not optimized for VR but i think that as there is one moment where enough frames are generated indicates, that maybe it’s worth a try to solve this. Of course only if the devs see it’s the same and not if the internals known by the them makes the attempt to solve it impossible (for example because it would need years to fix it).

Without sync to the headset there are very high fps numbers. so there is no need to change the headset but allow the engine to deliver what’s possible. and if the Rift gets a multiple of 80 fps it’s fine.