Any way to get the GPU bound time in milliseconds?

I’m trying to write a script (C++ or Blueprint) which needs access to the GPU bound time so I know exactly how long a frame took to process on the GPU.
I know you can use the delta on a frame tick - but this is similar to using Stat fps and it tells you the frame rate which locks to 90fps even if a frame only takes 5ms to render.
Does anyone know if there’s a way of finding out the render time of a frame in milliseconds?
Using the SteamVR>Settings>Performance>Display Frame timing shows the actual cpu/gpu bound time of each frame so it should be possible no?


/** How many cycles the renderthread used (excluding idle time). It's set once per frame in FViewport::Draw. */
extern RENDERCORE_API uint32 GRenderThreadTime;
/** How many cycles the gamethread used (excluding idle time). It's set once per frame in FViewport::Draw. */
extern RENDERCORE_API uint32 GGameThreadTime;
/** How many cycles it took to swap buffers to present the frame. */
extern RENDERCORE_API uint32 GSwapBufferTime;

const double CurrentTime = FApp::GetCurrentTime();
        const double DeltaTime = CurrentTime - FApp::GetLastTime();

        // Number of milliseconds in total last frame
        const double RawFrameTime = DeltaTime * 1000.0;

        // Number of milliseconds the gamethread was used last frame
        const double RawGameThreadTime = FPlatformTime::ToMilliseconds(GGameThreadTime);

        // Number of milliseconds the renderthread was used last frame
        const double RawRenderThreadTime = FPlatformTime::ToMilliseconds(GRenderThreadTime);

        // Number of milliseconds the GPU was busy last frame
        const uint32 GPUCycles = RHIGetGPUFrameCycles();
        const double RawGPUFrameTime = FPlatformTime::ToMilliseconds(GPUCycles);

Brilliant! That’s the stuff!
Cheers @mordentral :slight_smile:

Hey @mordentral (or anyone else that knows…)

The above code all works if I comment out the call to RHIGetGPUFrameCycles(); but adding that in does throw a linker error.
I have added the RenderCore module in the build.cs and have tried including DynamicRHI.h but it still throws the following if I try to compile with a call to RHIGetGPUFrameCycles();

The rest works though!

Any ideas what I’m missing that causes that lnk2001 ??

Thanks again

Found out it also needs the “RHI” module adding to the dependencies in the Build.cs.

Haha - me again!

So that code kinda works but as far as i can tell it actually just pulls the ‘rounded up’ frame time.

For example:
SteamVR is showing 6ms per frame on GPU and 3ms per frame on CPU.
The RawRenderThreadTime and RawGPUFrameTime from that script are both returning ~11ms - obivously rounding off to the 1/frame-rate with the frame-rate maintaining 90fps.

Any idea how I can pull the ‘6ms’ from within UE?