VR huge performance spikes, SteamVR crashes

Development Platform & Builds XR Development
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Hi everyone!
One of my team members encountered strange performance spikes in our VR project and I have no idea what could it be.

We have 3 game builds.

  1. First one was made back in January and have no performance issues.

  2. Second one was made in February and have performance issues (image.png). All this spikes caused by EndFlushResourcesRHI and Culling taking too long. It starting to happens after spending some time just standing in place and looking at different directions. At the end it leads to SteamVR crashing.

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  3. Third build was made in February, BUT from OLD January commit, and guess what, It’s having same performance issues.

Interesting thing is that from January to February GRAPHICALLY in the project nothing have changed: no new actors was placed in the world, project settings was not changed in any way, material was not changed in any way. Only new sounds was added.

I tried to disable culling, which only delayed performance spikes. This got me thinking that it might be some hardware issue, but teammate is ensuring us that his system and machine was not changed in any way (again, only we having this issue).

Any one have any idea what it could be?

2

The culling system blocking is likely just a symptom of something else. It works by polling the GPU until the work is done. If something else is holding up the GPU, it’s going to show as the flush blocking until whatever is holding it up is done.

I remember having similar issues with SteamVR in UE4 (although without crashing), and could never figure out the cause.

The first thing to check is if your render is taking up that time. If not, profiling with something like Nvidia Nsight Systems might help seeing what is using the GPU.