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RADV Finally Picking Up Support For Conservative Rasterization

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  • RADV Finally Picking Up Support For Conservative Rasterization

    Phoronix: RADV Finally Picking Up Support For Conservative Rasterization

    The RADV Mesa-based Radeon Vulkan driver is picking up support for another extension...

    http://www.phoronix.com/scan.php?pag...-Rasterization

  • #2
    Is there a hardware reason for not supporting VK_EXT_conservative_rasterization on older AMD gpus?

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    • #3
      TemplarGR Vega is the first AMD GPU to support conservative rasterization. CR could theoretically be implemented in software (enlarge every triangle to make sure all pixels are sampled), but that's slow, so not very useful.
      Last edited by juno; 09-12-2018, 08:18 PM.

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      • #4
        Originally posted by TemplarGR View Post
        Is there a hardware reason for not supporting VK_EXT_conservative_rasterization on older AMD gpus?
        Vega was fist to have the DSBR (Draw-Stream Binning Rasterizer) engine.

        From https://radeon.com/_downloads/vega-w...er-11.6.17.pdf

        These optimizations can significantly reduce off-chip memory traffic, boosting performance in memory-bound scenarios and reducing total graphics power consumption. In the case of “Vega” 10, we observed up to 10% higher frame rates and memory bandwidth reductions of up to 33% when the DSBR is enabled for existing game applications, with no increase in power consumption.

        Even larger performance improvements are possible when developers submit geometry in a way that maintains screens pace locality or in cases where many large overlapping polygons need to be rendered. For example, performance more than doubles in one professional graphics workload, the energy01 test in SPECviewperf ® 12, thanks to the DSBR.
        Also: https://techreport.com/review/31224/...architecture/3

        Nvidia added tiled rendering in Maxwell, though I think they've never publicly admitted this. Imagination has long used it in their mobile GPUs, I think.

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        • #5
          Thank you for the replies guys. Yeah i remember reading about tiled rendering for Nvidia and VEGA, just needed a confirmation. It's a nice extension to have, 7nm can't arrive fast enough so i can replace my Tonga

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          • #6
            @Michael:

            I hereby issue a formal (and hopefully fun) challenge: The next 100 articles you write, could you try to not use the word "finally" in either the Header or the Lede? =)

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            • #7
              While AMD implemented both technologies in the same generation, conservative rasterization is unrelated to the DSBR though. The binning/tiling is a rather implicit bandwidth optimisation. CR is an explicit operation, telling the rasterizer to include every pixel that the primitive touches instead of sampling at specific values.

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              • #8
                On the point of Vega's (still?) unique support of inner conservative rasterization, has anybody actually implemented some reasonable form of on-GPU occlusion culling with it yet? AFAIK, that is the primary selling point of the tech, but I have heard nothing further about it since release.

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