One big area that we haven't yet addressed which needs investigating is multiple GPU support - this can be a tricky area to get right.
The way DirectX11 handles multiple GPUs is “AFR” or Alternate Frame Rendering, which as the name suggests means if you have two comparably powered GPUs they simply take turns rendering frames. This is in many respects the easiest approach to take – and is a great way of making your game CPU bound! So possibly our Mantle version could show some big improvements when using this method.
However, with the independent control over the GPUs Mantle gives us, we could approach the problem very differently - for example one GPU could be rendering the basic geometry in the scene, while another handles lighting and shadows for the same frame, with the final image composited at the end. This may also provide a route for when GPUs aren’t of a comparable power level – for example an integrated APU motherboard coupled with a desktop GPU. It’s the potential for completely new approaches like this which excites me the most about Mantle and the APIs which will follow it.
