We implemented an experimental technique called heterogeneous multiadapter using Epic Games' DX12 Unreal Engine 4. This technique allows us to split the rendering workload across an integrated Intel GPU and a discrete NVIDIA GPU simultaneously maximizing performance.
We recognized that most mixed GPU systems in the world were not making the most out of the hardware they had. So in our quest to maximize performance, we set out to enable separable and contiguous workloads to be executed in parallel on separate GPUs. One such example of separable workloads is postprocessing.
Virtually every game out there makes use of postprocessing to make your favorite games visually impressive; but that postprocessing work doesn't come free. By offloading some of the postprocessing work to a second GPU, the first GPU is freed up to start on the next frame before it would have otherwise been able to improving your overall framerate.