ValveSoftware
Issues with ReleaseMirrorTextureD3D11
I'm writing a background application that accesses the compositor output every frame. The application opens both eye mirror textures using GetMirrorTextureD3D11, reads the mirror texture SRVs with a compute shader, and copies a set of output to the CPU, blocking with the Map function until completion.
If I call ReleaseMirrorTextureD3D11 on the mirror textures directly after waiting on Map and copying the data, when I the next frame call GetMirrorTextureD3D11, it gets stuck serving the textures from the original frame over and over. This goes on for about three seconds until it serves fresh textures, and then repeats the cycle. Debugging with Nsight Systems, the committed VRAM ramps up to about 26GB under those seconds before evicting the allocations and allowing the new textures in. It does not actually fill up the VRAM, it only seems to retain the SRVs which show up as committed memory.
When shutting down the application with the D3D debugging layer, it reports a large number of live objects with refcount 0, seemingly matching the current number of SRVs.
D3D11 WARNING: Live Producer at 0x000001FF9F8BC110, Refcount: 835. [ STATE_CREATION WARNING #0: UNKNOWN]
D3D11 WARNING: Live Object at 0x000001FF9FBBCFB0, Refcount: 0. [ STATE_CREATION WARNING #0: UNKNOWN]
D3D11 WARNING: Live Object at 0x000001FF9FB14440, Refcount: 0. [ STATE_CREATION WARNING #0: UNKNOWN]
D3D11 WARNING: Live Object at 0x000001FF9FB207D0, Refcount: 0. [ STATE_CREATION WARNING #0: UNKNOWN]
...
If I call ReleaseMirrorTextureD3D11 on the next frame immediately before calling GetMirrorTextureD3D11, I get the correct compositor textures, but still get the same behavior with the SRVs being retained.
The weird part is, if I don't call ReleaseMirrorTextureD3D11 at all, everything behaves as expected, with no ramping up of committed VRAM, and no live objects when exiting. I'm still hesitating to refrain from calling it, since it has to have some purpose, right?
Tested with a Valve Index on SteamVR 2.10.1 on Windows 10, using a RTX 4070 with driver version 560.94
I'm not sure what is causing the problem you are seeing, but you should only need to call GetMirrorTextureD3D11 once per eye, reuse the same D3D objects each frame, and then only call ReleaseMirrorTextureD3D11 on shutdown (which is optional, since SteamVR should clean it up for you if you don't).
Thanks. I've been doing it completely wrong then by requesting and releasing the texture each frame. The header comments are very ambiguous about the texture usage and lifetime. Here is the code I ended up with BTW: https://github.com/Rectus/openvr_ambient_light/blob/main/d3d11_renderer.cpp#L170
Does this apply to the textures from the camera API as well? Those functions also retrieve the current frame header, so it would make sense to call them every frame.