Trick to tell AMD and Nvidia drivers to use the most powerful GPU instead of a lower-performance (such as integrated) GPU

gpu.cpp

#ifdef _WIN32
// Use discrete GPU by default.
extern "C" {
  // http://developer.download.nvidia.com/devzone/devcenter/gamegraphics/files/OptimusRenderingPolicies.pdf
  __declspec(dllexport) DWORD NvOptimusEnablement = 0x00000001;
​
  // http://developer.amd.com/community/blog/2015/10/02/amd-enduro-system-for-developers/
  __declspec(dllexport) int AmdPowerXpressRequestHighPerformance = 1;
}
#endif

Here is another AMD link: https://gpuopen.com/amdpowerxpressrequesthighperformance/

Dumb question: Are these relevant in Linux (or OSX for that matter)?

No, this is not relevant for anything other than Windows.

More dumb question: There's nothing similar for Intel (integrated HD Graphics), right?

More dumb question: can I do this somehow from a managed C# application? It does Pinvoke for the purpose of calling native algos, but how would I extern "C" { __declspec(dllexport) ... } such properties to be picked up by the drivers? Can any of my native DLLs export this and it will be picked up?

and is there analogue to force rendering on Intel discrete GPU?

right

Intel always uses the Power Plan. If there is a Intel ARC GPU and an Intel UHD Integrated and the power plan says to maximize performance it will use the Intel ARC

managed

Based on what I read and tried for AMD at least it uses a utility that scans for the string of AmdPowerXpressRequestHighPerformance before it's executed and thus A: you can't inject DLL code in memory B: you can't use a wrapper for it (TESTED) as the graphics selection isn't inherited between processes. C: People already tested putting the code in the DLL on both AMD and NVIDIA and it does nothing. It has to be the main EXE

Anyone Figure out how to programmatically use one of AMD's EXE's and NVIDIA to add Graphics entries directly to the UI instead of dealing with this madness which doesn't support wrappers or DLLs. I checked the registry it doesn't appear to do anything on an AMD machine tested with 2019 AMD Software. 2020+ AMD Software ignores switchable graphics entries and only uses the powerplan fallowing intels footsteps. Before Windows Added Graphics Entry Options in windows 10 (2020?) AMD and NVIDIA Software was the only way of setting the preferred graphics processor per exe

Dumb question: Are these relevant in Linux (or OSX for that matter)?

If they have the right AMD drivers it should in theory work for linux based on how it's detected of literally dumping strings and looking for the field.
MacOs doesn't use NVIDIA in any recent years nor AMD they create their own now I believe and also I believe on macos only supports onegpu. The GPU being either intel iris neither integrated nor dedicated, or their own