Question Random spikes

Hey guys. We have random spikes in our StreamVR game. I cant for the life of me find out why, it never occurs on the same spot in the scene so its not scene related it seems. Our scripts takes almost nothing so its not that




Hardware:
AMD 5950x
Nvidia 3090 drivers: 526.98

 

The highlighted frames GPU seems to take up the most. Can be anything from drivers, to nvidia settings, etc
If it's not noticable in-game I wouldn't worry too much about it

 

It's any thing from a slight lag to a spike with reprojection :/

 

I have read there are problems with 30xx series and VR, maybe that's what I am experiencing?

 

Looks broken? Says 14.080 ms is spent in Device.Present but if I expand that node the children says 0? Does this tell you anything?

 

My main monitor is a 144hz screen. And the valve Index runs in 90hz. The spikes magnitude is pretty much random. It doesn't seem to be tied to a fixed refresh rate.

Edit: i will try to see if I can repro.

 

Here is a example of a less severe lag



And here is another example of a more severe lag



This is with 144hz display rate on main monitor. Will try to lower refrshrate now.

 

Here with my monitor at 60hz

 

We are on built in forward rendering

 

Same thing in an empty project with onlyxr and steamvr xr plugin



edit: by mistake did this in 2021 LTS while our game for now uses 2020 LTS

 

Thanks for taking your time. Thing is if i just run the game without profiling i get these spikes to, i can both see them in. SteamVR frametime window in headset and I can observe the actual lag.

 

I recorded this little demo without profiling, though recording with OBS which skews the result a little bit.

You can see both pink spikes (reprojection) and the smaller yellow spikes thats just a smal lag but still noticble.

edit: Funny enough my benchmarking thats going on in the background (this is a precorded path) does not notice a big impact on the perf, though I do remove the top and min 1% frames from the result and those spikes are probably not in the statstics because of that

With OBS:
Highest Frametime: 2.7177
Lowest Frametime: 1.3324
Avg framerate: 1.832094

Without OBS:
Highest Frametime: 2.6185
Lowest Frametime: 1.2623
Avg framerate: 1.75618

Though I must give you guys credit that GFX jobs finally does a difference, above is with gfx jobs and below without. A 10% increase in perf!

Without OBS and without GFX jobs:
Highest Frametime: 2.8731
Lowest Frametime: 1.3738
Avg framerate: 1.937669