Suggestions for troubleshooting VR framerate issues with AC online / AI events

[Locoblade]

After having massive issues with VR framerate at the recent RD Road Atlanta GT3 race in Asseto Corsa, I had a hunch that I'd perhaps installed one or two mods/apps that were causing issues so decided on a fresh install, only copying across downloaded tracks and a few other bits from the user folder in My Documents

Spec wise the machine should be up to the job of running this game in my Samsung Odyssey headset at 90fps, a recently built Ryzen 3600 with 16Gb of 3600 RAM, an RTX 2070 Super GPU and Win 10 on an M2 SSD, significantly higher spec than a couple of others racing in VR in the same event that had no issues.

Sadly the reinstall hasn't helped, if I run on my own at say Road Atlanta it's fine, a solid 90fps, but if I start a race with a grid of 24 AI cars, it immediately drops to about 55-65fps (~18-20ms frame time) even whilst sitting on the line not moving and only improves if you let all the other cars get about half a lap away completely out of sight. It does seem to be somewhat track related as I get about 10fps more if I run the same race at Spa for example, but still a long way off being acceptable.

I've used MSIAfterburner, GPUz and HWinfo logging options to try and diagnose the bottleneck but I'm not sure I see anything obvious. The GPU is running at ~60% load, no single CPU core is being maxed out and memory usage is about half of what's available. The only thing I think is slightly strange is that the GPU is reporting to be Reliability Voltage limited during the game which I thought odd given the GPU load is barely above 50%? The GPU itself seems OK though if I run say a blender benchmark it will run at 100% without issue giving a middle of the road score for a 2070S. I've also tried adjusting Steam settings for the app to reduce/remove supersampling etc and also reset the app specific settings back to default in the nVidia drivers. At this stage I'm not certain if it's hardware or game related but If anyone has some suggestions on what else I can look for or a better way of logging that will help identify the issue that would be great.

cheers

 

[GeekyDeaks]

Hi @Locoblade, I'm not sure this is going to be a huge amount of help, but I did a quick test at the same circuit with 24 cars sitting at the start and this was my system loading according to fpsVR:

I then upped the AI count to 29 to push it over the edge and this is what I got:

Strangely, the GPU and CPU occupancy goes down slightly... I'm going to do a bit of digging as to why this would be the case

Regarding the voltage cap, I'm assuming you have it set to 100% power in msi?

I can share my AC settings if you want. I have just about everything turned off! Shadows were the main killer IIRC

 

[Locoblade]

Cheers mate, thats actually really useful. Knowing your spec of machine and headset shows there's definitely something wrong or misconfigured with mine somewhere as I believe my CPU and GPU are both more powerful whilst my headset is lower resolution, so I shouldn't be seeing significantly less fps than you are. I've not used fpsVR before so will give that a go to get some direct comparisons as that looks like that shows quite clearly whether it's a CPU or GPU bottleneck.

cheers

 

[Locoblade]

Hmm, so installed FpsVR and here's the results sitting on a 32 car grid at RA. Frametime sporadically spiking and being limited due to what looks like a GPU restriction, but at the same time the GPU is only at 41% usage?!
Looking at the raw numbers from the logging it seems most of the frames are around 10ms which is fine, but then you get sudden spikes of 20+ms as I managed to capture in the screenshot #confused

 

[Deleted member 197115]

Is your monitor variable refresh rate (FreeSync/GSync).
Set Monitor Technology to Fixed Refresh.

And disable this if you are on Win v2004

 

[Locoblade]

Thanks, it's just a boggo 60hz 1080p display but I don't see that setting in nVidia control panel, perhaps only visible with GSync/Freesync enabled?

As to the GPU scheduling, just checked and that's disabled already.

 

[Locoblade]

Just to add, if I run the standard AC benchmark around Spa, that ticks along nicely at about 6-8ms frametime, although I suspect the benchmark is basically a replay not needing to calculate real-time physics of AI cars as it obviously plays out exactly the same scenario every time

 

[Deleted member 197115]

What happens with so many opponents cars that they are taxing rendering thread, reason your GPU is idling.
Each frametime consist of CPU prepare draw call portion and GPU rendering part. AC as most others using single rendering thread and adding a lot complex object to the scene (opponent cars in this case), making its job harder.
Few things:
- Not all cars are created equal, some are more complex than others, some don't have LODs. Kunos OEM content is usually fine except some outliers like Porsche 911 GT3 and RSR.
- Try play with CM LOD settings, like forcing LOD B for opponent cars
- Lower the number of opponents, 32 is way too much for any system.

And one more, I haven't played with that myself by there is hidden param in graphics_adjustments.ini to control number of LODs and visible cars
[VISIBLE_CARS] ; hidden ; four values are for: LOD A, simplified render without some extra bits, LOD C and LOD D MAIN=3, 8, 16, 28 GBUFFER=3, 8, 16, 16 SHADOWS=3, 6, 6, 16 SPECTATING_MAIN=6, 20, 40, 200 SPECTATING_GBUFFER=3, 12, 24, 24 SPECTATING_SHADOWS=3, 12, 12, 24

 

[Deleted member 197115]

Just to add, if I run the standard AC benchmark around Spa, that ticks along nicely at about 6-8ms frametime, although I suspect the benchmark is basically a replay not needing to calculate real-time physics of AI cars as it obviously plays out exactly the same scenario every time

Physics is on different from rendering thread (threads).

@Moderator, can we please move this to AC subforum.

 

[Locoblade]

Thanks, just to say I'm only using 32 (Kunos GT3 cars like Audi R8 LMS and Mclaren 650S GT3) in an attempt to replicate the problems I initially had in an RD online GT3 race that had ~30 entrants, to an extent its certainly exacerbated by that particular track and obviously the numbers on the grid, but it's an event where others were racing in VR using equal or lower spec hardware yet didn't experience any issues so I don't think I'm chasing an unattainable goal.

 

[pattikins]

Thanks, just to say I'm only using 32 (Kunos GT3 cars like Audi R8 LMS and Mclaren 650S GT3) in an attempt to replicate the problems I initially had in an RD online GT3 race that had ~30 entrants, to an extent its certainly exacerbated by that particular track and obviously the numbers on the grid, but it's an event where others were racing in VR using equal or lower spec hardware yet didn't experience any issues so I don't think I'm chasing an unattainable goal.

I have very similar PC specs - Samsung Odyssey +, R5 3600x, GTX 1080ti, & 16gb @ 3200mhz - & I also ran in to the same problems with the RD AC Sunday night gt3 races. Up until about 6 weeks ago I was a regular @ the Sunday night events, but my PC (cpu) couldn't cope with 30+ cars on the grid. It's not a new issue with regard to VR & large grids in AC.

It might be worth trying to run your Odyssey @ 60hz or in reprojection (45fps) mode. I'd also turn off all the AC apps during the qualy & race. I remember reading that running the cpu with hyperthreading off can help - it's not a road I wanted to go down for a single game.

 

[pattikins]

View attachment 386479

Do you have your foot resting on the brake pedal?

 

[Locoblade]

Do you have your foot resting on the brake pedal?

I used to have that with the same pedal setup as Geekydeaks, modified G25/29 pedals with a load cell. The load cell we use is very sensitive and I stuggled to hover my foot completely off the brake pedal for long periods so I ended up trimming out the bottom 2-3% of the brake pedal in the game setup to stop it dragging the brake whilst allowing my foot to rest touching the pedal.

 

[GeekyDeaks]

Do you have your foot resting on the brake pedal?

Oh, good spot! I think probably yes as I tend to do it when sitting idle in the rig and the other screenshot seems to be ok, but I'm going to double check when I finish work

 

[Locoblade]

I have very similar PC specs - Samsung Odyssey +, R5 3600x, GTX 1080ti, & 16gb @ 3200mhz - & I also ran in to the same problems with the RD AC Sunday night gt3 races. Up until about 6 weeks ago I was a regular @ the Sunday night events, but my PC (cpu) couldn't cope with 30+ cars on the grid. It's not a new issue with regard to VR & large grids in AC.

It might be worth trying to run your Odyssey @ 60hz or in reprojection (45fps) mode. I'd also turn off all the AC apps during the qualy & race. I remember reading that running the cpu with hyperthreading off can help - it's not a road I wanted to go down for a single game.

Interesting you have very similar specs and the same issue with the Sunday races.

Do you use SOL? I tried a few things last night and found that by disabling SOL in CM and using NaturalMod instead I gained about 10fps on a 32 car grid and could run a 24 car grid with frametimes in the green all bar the odd very occasional blip. Thats by far the biggest gain I've seen from a single change so will continue tonight to see if I can further improve things.

 

[Locoblade]

Oh, good spot! I think probably yes as I tend to do it when sitting idle in the rig and the other screenshot seems to be ok, but I'm going to double check when I finish work

I only noticed when watching replays and my brake lights were randomly flashing along the straights etc, I don't think it was sufficient to cause a significant difference to lap time etc but must have been annoying for those following me assuming it was doing it in game as well!

 

[pattikins]

Interesting you have very similar specs and the same issue with the Sunday races.

Do you use SOL? I tried a few things last night and found that by disabling SOL in CM and using NaturalMod instead I gained about 10fps on a 32 car grid and could run a 24 car grid with frametimes in the green all bar the odd very occasional blip. Thats by far the biggest gain I've seen from a single change so will continue tonight to see if I can further improve things.

I don't use SOL or CM, but I'll have a look @ the NaturalMod if it helps with the framerate in VR.