AMD has made its CrossFire API available for free via GPUOpen – the company’s rival to NVIDIA’s GameWorks – making it easy for game developers to utilise its multi-GPU solution, which should be of particular benefit to indie developers. Since the launch of its Radeon Software Crimson Edition drivers, AMD has been working toward CrossFire integration with DirectX 11, and this latest step is designed to further unlock the API’s potential. The accompanying guide recommends alternate frame rendering (AFR) as the most effective way of exploiting CrossFire capabilities.
“Gaming at optimal performance and quality at high screen resolutions can sometimes be a demanding task for a single GPU,” the new guide on the GPUOpen site reads. “4K monitors are becoming mainstream and gamers wishing to benefit from the quality provided by 8 million pixels at comfortable frame rates may need a second GPU in their system to maximize their playing experience. To ensure that performance scales with multiple GPUs some work is usually required at the game implementation level.”
“Alternate Frame Rendering (AFR) is the method used to take advantage of Multiple GPUs in DirectX® 11 and OpenGL® applications,” the post adds.” The Crossfire guide describes AFR and how it is implemented in AMD drivers. The guide also provides recommendations on how to optimize a game engine to fully exploit AFR. As described in the guide the goal is to avoid inter-frame dependencies and resource transfers between GPUs. Transfers are initiated by the driver whenever it determines that a GPU has a stale resource. Transfers go through the PCI Express® bus and this is usually an expensive operation.”
AMD has also released a detailed guide for using CrossFire for Direct3D 11 applications [PDF].
