Could CPU occupacy 100% be wrong?

[Alen Pecanin]

Hey guys,

need some help and adviced from my fellow AC sim racing enthusiasts. I've got a weird fps slowdown and need feedback.

I've done a fresh install of AC, which I havent played in 4+ months. So now Im back and have time for sim racing, so I downloaded content manager, got the full version too, and did some nice downloading of high quality tracks and cars. I love the game and the experience is great.

I play in VR and have a pretty OK computer I believe, but after installing content manager, SOL, all the extras and pluggins, setting everyhing on high and something on ultra, and enabling all extra effects, the FPS goes down. Before I give you my horror story, here are my rigs specs:
CPU: i7 6700k
GPU: GTX Titan X 12GB (1st gen Titan X/Maxwell)
RAM: 16GB 4000mhz
PSU: 750w
cooling: Corsair h110i-something
storage: 500GB SSD, 250GB SSD, 1TB HDD (This is where AC is installed)
VR: Rift CV1

I loaded up Kyalami 2016 version in practice mode and played for maybe 1 hour to make a setup for my GT4 AMG GT Mercedes from Guerilla mod.
After this I loaded up a race weekend with 23ish opponents on the same track. 25min qualifying and 25 laps race.
The qualifying was playable, but when the race started, 2 laps into it the game got into slow motion and was unplayable, with the message "CPU Occupacy 100%" showing up. I got out of the race and exited the game to desktop.

So I went to check the pc and what was wrong, but the CPU never went over 32 degrees according to the logs on my software even on full load. But the GPU went to the maximum degree limit which is set on 83 degrees. I understand that all these extra mods with SOL and crazy shaders and all require extra, but shouldnt it show "GPU occupacy 100%" if the GPU is the bottleneck here? As I dont see the CPU dying on my monitoring software, but the GPU is.
I didnt have time to set the settings to medium and play again, but will test next time how it goes.
Also, would the 1080TI be better performing than my 12GB Titan X on VR, should this solve my problem? Or does one need to fork out for the 2080 RTX or 2080 Ti card to play with everything on max in AC now, in VR?

 

[FuzzyHead]

I've very occasionally had the "CPU Occupancy 100%" message and a slide show. In each case, the cause was a massive (off screen) pile-up between the AI. The frame rate returned to normal once all the wrecked cars had retired. Is it possible that could have been the cause?

 

[Billy Pilgrim]

There’s a long long list of cars to use before getting to that Guerilla GT4 mod.

And I’m pretty sure the 100% occupancy message is right.

 

[Stereo]

100% occupancy generally happens on the main core of the cpu which has to run the non-multithreaded parts of AC, fmod, directx, etc. If you have a multicore cpu this doesn't put much of a load on it cause it can move around which core is calculating things, but it depends on single thread performance.

As a general principle multithreading can only work effectively on things that don't depend on each other. So for example if you're simulating 2 cars in different parts of the racetrack, neither has to know where the other car is to calculate tire temperatures, g forces, etc. So large numbers of AI just spread across a multicore cpu. On the other hand collisions need to be completely synchronized so every other calculation waits while it figures out which cars are running into each other.

I don't know how likely it is to be a bottleneck but you might also check out your replay settings, that's something that could get worse over a session if it fills whatever in-memory cache and has to go to a hard drive.

 

[Alen Pecanin]

I've very occasionally had the "CPU Occupancy 100%" message and a slide show. In each case, the cause was a massive (off screen) pile-up between the AI. The frame rate returned to normal once all the wrecked cars had retired. Is it possible that could have been the cause?

Not sure, I paused the game after 4-5 seconds with the CPU-message, and closed the game right after that. So I didn't check. I was on the 3rd or 4th lap into the race when this happened, I believe. Not sure if there are any bugs with AI on this track. Dont know of any known issues.

There’s a long long list of cars to use before getting to that Guerilla GT4 mod.

And I’m pretty sure the 100% occupancy message is right.

Hey, not sure what you mean by that?

100% occupancy generally happens on the main core of the cpu which has to run the non-multithreaded parts of AC, fmod, directx, etc. If you have a multicore cpu this doesn't put much of a load on it cause it can move around which core is calculating things, but it depends on single thread performance.

As a general principle multithreading can only work effectively on things that don't depend on each other. So for example if you're simulating 2 cars in different parts of the racetrack, neither has to know where the other car is to calculate tire temperatures, g forces, etc. So large numbers of AI just spread across a multicore cpu. On the other hand collisions need to be completely synchronized so every other calculation waits while it figures out which cars are running into each other.

I don't know how likely it is to be a bottleneck but you might also check out your replay settings, that's something that could get worse over a session if it fills whatever in-memory cache and has to go to a hard drive.

You might be on to something with the replay-thing. I did actually change replay settings to maximum quality and maximum size before the race. I did 1 race the day before on Road Atlanta with this new SOL mod and all the filters enabled, the game looks amazing on replays. I had some nice battles on the track, but the replay only captured the first half of my race, not all of it. So I maxed out everything before this race to record everything, so I can save the best moments for later watching.

I'll turn the replay completely off next time I play, and have the same conditions, and see If this happens.

 

[onearmedbandit46]

I've got an i7 9700, RTX2080 and 32gb ram and run in VR on Vive Pro. With that system I still can't run every thing on high, ultra and all extra effects. I used this guide to get a visual fantastic experience at 90fps.

AC VR Settings.docx

drive.google.com

I believe the guy who made it is a member here, Andrew_WOT

 

[Sascha Guenther]

I´ve checked this attached sheet and wondered: why has he unticked Vsync in his settings since he runs on a 60 Hz framerate? Whats the benefit from that? And furthermore you should activate FXAA in the AC settings, too, since otherwise CM does not work with the graphic adjustments correctly. Its mandatory to have FXAA activated to use the graphic adjustments settings.

 

[Deleted member 197115]

VSync should be disabled for VR otherwise HMD can start syncing on monitor refresh rate instead of 90hz (doesn't happen on all systems).
FXAA is irrelevant as none of Post Processing AA methods that require it work in VR.
From our tests even FXAA on its own does not work in AC VR if MSAA is active.

 

[Sascha Guenther]

Ok, makes sense. Sorry I don´t use VR so thats why I wondered.

 

[onearmedbandit46]

VSync should be disabled for VR otherwise HMD can start syncing on monitor refresh rate instead of 90hz (doesn't happen on all systems).
FXAA is irrelevant as none of Post Processing AA methods that require it work in VR.
From our tests even FXAA on its own does not work in AC VR if MSAA is active.

I was hoping you'd see that post otherwise I was going to direct him to ask you.

 

[Alen Pecanin]

Just for info guys, I set the replay settings to absolute minimum on everything. Quality, recording, all. Problem is totally gone and got a massive FPS gain!

 

[Mascot]

I hope this helps someone else as it's been driving me bonkers for a few days now, but my performance absolutely tanked recently and task manager showed it was because of extremely high CPU usage. After trying all of the various suggestions I bit the bullet and deactivated the CSP and went back to vanilla AC (still launched through CM, just with the CSP unticked in settings).
With the CSP off, performance went through the roof with 40 car grids exceeding 45fps to achieve a constant ASW in VR, whereas before I was getting ~25fps with half a dozen cars. Vanilla AC still looked pretty good and it's only 3D mirrors I'd really miss so I figured I'd stick with it purely for the rock-solid performance.
Anyway, I thought I'd try reactivating the CSP as one final hurrah and guess what? All my performance is back, with all apps and settings as before.
The TDLR here is: if your peformance tanks, deactivate the CSP, use it in that state in a race or two (it'll require a few reloads as it'll fail a few times as various incompatible apps get automatically deactivated one by one), then simply tick CSP again to 'reset' it.
Worked for me and I sincerely hope it works for you.

 

[Sascha Guenther]

I hope this helps someone else as it's been driving me bonkers for a few days now, but my performance absolutely tanked recently and task manager showed it was because of extremely high CPU usage. After trying all of the various suggestions I bit the bullet and deactivated the CSP and went back to vanilla AC (still launched through CM, just with the CSP unticked in settings).
With the CSP off, performance went through the roof with 40 car grids exceeding 45fps to achieve a constant ASW in VR, whereas before I was getting ~25fps with half a dozen cars. Vanilla AC still looked pretty good and it's only 3D mirrors I'd really miss so I figured I'd stick with it purely for the rock-solid performance.
Anyway, I thought I'd try reactivating the CSP as one final hurrah and guess what? All my performance is back, with all apps and settings as before.
The TDLR here is: if your peformance tanks, deactivate the CSP, use it in that state in a race or two (it'll require a few reloads as it'll fail a few times as various incompatible apps get automatically deactivated one by one), then simply tick CSP again to 'reset' it.
Worked for me and I sincerely hope it works for you.

@Mascot have you also read my post in the gtp forum some days ago? For me the culprit was to deactivate all apps at once and then trial-and-error which one would be the bad one. I still haven´t figured out which one but I strongly assume it is a. weatherFX app from CSP (it collides with the SOL from Peter Boese) or b. the sidekick app (I installed a newer version without deleting the old one first and it has a strong influence in CM´s lap time settings).
I never thought that AC with CSP can run that great. I mean, I have everything maxed out in settings, even in AC and it runs buttersmooth with 60 FPS locked.

 

[Mascot]

@Mascot have you also read my post in the gtp forum some days ago? For me the culprit was to deactivate all apps at once and then trial-and-error which one would be the bad one. I still haven´t figured out which one but I strongly assume it is a. weatherFX app from CSP (it collides with the SOL from Peter Boese) or b. the sidekick app (I installed a newer version without deleting the old one first and it has a strong influence in CM´s lap time settings).
I never thought that AC with CSP can run that great. I mean, I have everything maxed out in settings, even in AC and it runs buttersmooth with 60 FPS locked.

I did, yes - thanks. I tried all that (and all other suggestions) but as it turned out, simply 'resetting' the CSP by turning it off and on again did the trick. I'm mightily relieved.

 

[Deleted member 197115]

Interesting experience, did you try to share it on CSP discord?

 

[Mascot]

Interesting experience, did you try to share it on CSP discord?

You just open yourself up to ridicule and sarcasm there from certain key members no matter how you try to contribute, so no. It's a cess pit that requires waders before entering.
*shrugs*
It's a shame, but kids will be kids.

 

[Trava]

That's funny, I haven't seen you contributing much. For sure not more than the "key members" you speak about.
Maybe if you stopped hoarding every single low quality convert and rip out there and asking how to fix problems that do not happen with any decently made mod you wouldn't be ridiculed so hard.

@Alen Pecanin Make sure AC isn't pegging one of your CPU cores to 100%, from what I remember this game doesn't really multithread that well.

@ down
talk ****, get hit

 

[Deleted member 197115]

@Mascot, my man, they've got you even here. No place is safe.

 

[Mascot]

@Mascot, my man, they've got you even here. No place is safe.

Totally expected. Nicely reinforces my point.

 

[Deleted member 197115]

Totally expected. Nicely reinforces my point.

Funny that the real biggest contributors are the nicest people imaginable. Paradox.