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• DIRECTX 12 GRAPHICS CARD DRIVER

Data transfer bandwidth between GPUs is very limited and copying too much stuff can make the transfers the bottleneck in the rendering process.

DIRECTX 12 GRAPHICS CARD DRIVER

In practice, the display driver needs hints from the application to understand which resources it must copy from one GPU to another and which it should not.

Namely, temporal techniques that create data dependencies between consecutive frames make it challenging to execute alternate frame rendering (AFR), which still is the method of choice for distribution of work to multiple GPUs. But why start doing something manually that has been working automatically? Because, actually, for a good while before DirectX 12 arrived, the utilization of multiple GPUs has not been that automatic anymore.Īs rendering engines have grown more sophisticated, the distribution of rendering workload automatically to multiple GPUs has become problematic. With DirectX 12, this is not the case anymore. The application always saw one graphics device object no matter how many physical GPUs were behind it. Since the launch of SLI, a long time ago, utilization of multiple GPUs was handled automatically by the display driver. In the second part, I’ll describe a technique called frame pipelining - a new way for utilizing multiple GPUs that was not possible before DirectX 12. Please look for further details in the documentation itself.

In this first part, I’ll explain how multiple GPUs are exposed in the DirectX API, giving some pointers to the API documentation. Now, DirectX 12 gives that control to the application. In previous versions of DirectX, the driver had to manage multiple SLI GPUs. This blog post is about explicit multi-GPU programming that became possible with the introduction of the DirectX 12 API.