If I take it from what happened on PS3, one possibility could be that the CU would actually drive the engine. On PS3, initially the PPU would drive the SPU jobs by distributing and feeding the work to the SPUs. But the PPU itself was actually a bottleneck in this, and making the SPU the main job distributer turned out to be more efficient, leaving the PPU to other work.
I don't know if this is possible with CUs, but the AMD presentation suggests that it just might be. And in that case, that would indeed free up additional CPU resources, which are currently claimed to be a more likely bottleneck than GPU resources are.
I don't know if this is possible with CUs, but the AMD presentation suggests that it just might be. And in that case, that would indeed free up additional CPU resources, which are currently claimed to be a more likely bottleneck than GPU resources are.