VR locked frame rate & Performance Measurements

Hello,

For my Bachelors Thesis I’m comparing techniques for improving performance in VR. For that I’m using nVidia’s fork of the Unreal Engine, specifically the MultiRes-4.11 branch.

As a metric for performance, I’m trying to use the frame rate, however it seems that the frame rate always has the HMDs maximum refresh rate as it’s upper bound, which in my case is the Oculus Rift DK2’s 75hz.

I already tried several console commands to increase frame rates or turn off vsync as well as trying to play around with and disable frame rate smoothing, with no success.

Is there anything else I should try before I start messing with engine code? Next I would try to change the DisplayRefreshRate of ovrHmdDesc of the Oculus SDK that is passed to the engine.

Alternatively, is there a better way to accurately measure performance? Maybe the time it takes the GPU to calculate a frame?