Get GPU memory usage programmatically

Question

I'm looking for a reliable way to determine current GPU memory usage preferably in C++/C . I have found many ways of obtaining usage like the following methods:

• Direct Draw
• DxDiag
• WMI
• DXGI
• D3D9

Those methods are not accurate enough (most off by a hundred megabytes). I tried nvapi.h but I didn't see anything that I could use to query for memory. I was thinking only the methods listed above were the only options but then I ran into a tool called GPU-Z that gives me accurate memory readings to the nearest megabyte even when OpenCL runs almost full load on my 580GTX. I can verify I am at the peak of my memory usage by allocating a few more megabytes before OpenCL returns Object_Allocation fail return code.

Looking at the imports from GPU-Z, I see nothing interesting other than:

kernel32.dll: LoadLibraryA, GetProcAddress, VirtualAlloc, VirtualFree

My guess is LoadLibraryA must be used to load a dll for querying the GPU memory and sensors. If this dll exists, where does it live? I'm looking for a solution for AMD and NVidia if possible (using different APIs is ok).

Answer 1

D3DKMTQueryStatistics is what you need.

Similar question has been asked here: How to query GPU Usage in DirectX?

Answer 2

cudaMemGetInfo (documented here) requires nothing other than the cuda runtime API to get free memory and total memory on the current device.

And as Erik pointed out, there is similar functionality in NVML.

Answer 3

Check out the function nvmlDeviceGetMemoryInfo in NVIDIA Management Library https://developer.nvidia.com/nvidia-management-library-nvml:

"Retrieves the amount of used, free and total memory available on the device, in bytes."

Don't know if AMD has something equivalent.