Current DXVK implementation (as of 2.3.1) seems to trigger SK_DXGI_PresentBase twice per frame

[Kethen]

In Wine, when dxvk d3d11.dll+dxgi.dll is installed to c:/windows/system32, SpecialK can still be hooked as local dxgi.dll/d3d11.dll placed next to applications

When loaded that way (SpecialK hooking DXVK d3d11.dll and dxgi.dll), below can be observed:

1. SpecialK actually hooks correctly, I was interested in the texture modding feature and both dumping and injecting were working
2. However Performance is degraded
3. Built in fps counter shows double actual application framerate

While I have not performed any runtime tracing to confirm this, this is likely caused by the fact that dxvk DxgiSwapChain::Present just calls DxgiSwapChain::Present1 with null pPresentParameters, firing both Present and Present1 hooks when an application uses Present

https://github.com/doitsujin/dxvk/blob/2b70ba8f7798107308a0c34358a9e83e77017dfd/src/dxgi/dxgi_swapchain.cpp#L305-L307

Perhaps a config options should be added to skip either DxgiSwapChain::Present1 or DxgiSwapChain::Present hooking/callback?

[Kaldaien]

Ugh.

I was hoping this issue would never come up. Figures it would be DXVK though.

I think the proper solution would be for SK to call Present1 (...) in its Present (...) hook and never call the original Present function. The reason I haven't done this is because there are some overlays that don't understand Present1. The Steam overlay was like that for many years.

[Kaldaien]

No wait, nevermind. This isn't fixable. The Steam overlay and RTSS will both crash if Present1 (...) is called.

This is better addressed if you contact the developers of DXVK instead.

[Kethen]

closing for now since doitsujin/dxvk#3966 was merged

while it fixed the double fps stats, it only partially fixed the degraded performance

another cause of degraded performance seems to be related to bool SK_D3D11_EnsureMatchingDevices (ID3D11DeviceChild *pDeviceChild, ID3D11Device *pDevice) and bool SK_D3D11_EnsureMatchingDevices (IDXGISwapChain *pSwapChain, ID3D11Device *pDevice) never matching on dxvk, causing vram/pcie bandwidth issue with imgui_d3d11

will be creating a new issue when I have a better grasp of the other cause(s) of degraded performance