AMD RDNA 3 GPU Architecture Deep Dive

AMD Addresses Controversy: RDNA 3 Shader Pre-Fetching Works Fine

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(Image credit: AMD)

Reports that AMD’s RDNA 3 GPUs have broken shader pre-fetch functionality aren’t accurate, according to a statement that AMD issued to Tom’s Hardware:

“Like previous hardware generations, shader pre-fetching is supported on RDNA 3 as per [gitlab link (opens in new tab)]. The code in question controls an experimental function which was not targeted for inclusion in these products and will not be enabled in this generation of product. This is a common industry practice to include experimental features to enable exploration and tuning for deployment in a future product generation.” — AMD Spokesperson to Tom’s Hardware.

AMD’s statement comes on the heels of media reports that the recently-launched Navi31 silicon in the RDNA 3 graphics cards have ‘non-working shader pre-fetch hardware.’ The source of the speculation, @Kepler_L2, cited code from the Mesa3D drivers that appeared to indicate the shader pre-fetch doesn’t work for some GPUs with the A0 revision of the silicon (CHIP_GFZ1100, CHIP_GFX1102, and CHIP_GFX110).

However, AMD’s statement says that the code cited by Kepler_L2 pertained to an experimental function that wasn’t intended for the final RDNA 3 products, so it is disabled for now. AMD notes that including experimental features in new silicon is a fairly common practice, which is accurate — we have often seen this approach used with other types of processors, like CPUs. 

For instance, AMD shipped an entire generation of Ryzen products with the TSVs needed to enable 3D V-Cache, but didn’t use the functionality until third-gen Ryzen. Likewise, Intel often adds features that might not make it into the final product, with its DLVR functionality being a recent example.

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