![]() Processing the same 16 pixels on 16 SPs will also take 4 clock cycles.īut there are reasons to believe that things happen the way we described. Scheduling the simultaneous processing one vec4 MAD operation on 4 quads (16 pixels) over 4 groups of 4 SPs will take 4 clock cycles (in terms of throughput). They can get away with being obscure about how they actually process the data because it could happen either way and provide the same effect to the developer and gamer alike. We certainly pressed them about how vertices and pixels map to SPs, but the answer we got was always something about how dynamic the hardware is able to dynamically schedule the SPs optimally according to what needs to be done. ![]() DerekWilson - Tuesday, Novemlink Honestly, NVIDIA wouldn't give us this level of detail.As a consequence, in this scenario 4 pixels are computed only by 4 SPs. Each vector instruction (inside the shader) is "mapped" as a sequence of scalar operations (a dot product beetwen two vectors is mapped as 4 MUD/ADD operations). Reading others articles the main idea that i realized is that a shader is computed by one and only one SP. ![]() I didn't found others articles over the web that speculate about this. Then, this assumes that each component of the pixel shader is computed horizontally over 16 SP (4pixel x 4rgba = 16SP). If i understood well this sentence tells that given 4 pixels the numbers of SPs involved in the computation are 16. Each block of 16 SPs shares 4 texture address units, 8 texture filter units, and an L1 cache." Now, rather than 4 pixel quads, we see 16 SPs per "quad" or block of stream processors. "It isn't surprising to see that NVIDIA's implementation of a unified shader is based on taking a pixel shader quad pipeline, and breaking up the vector units into 4 scalar units. epsil0n - Sunday, Novemlink I am not agree with this:.We can't tell if the difference we see in Oblivion is due to shader replacement, filtering, or some other optimization under R580. While we don't have the ability to specifically disable or enable optimizations in ATI hardware, Catalyst AI is the feature that dictates how much liberty ATI is able to take with a game, from filtering optimizations all the way to shader replacement. We can clearly see that G70 takes a performance hit from enabling high quality mode, but that G80 is able to take it in stride. Quality texture filtering on NVIDIA hardware, we ran a few benchmarks with as many optimizations disabled as possible and compared the result to our default quality tests. In order to understand the performance impact of High Quality vs. Thus, our tests will be done at default texture filtering quality on NVIDIA hardware. Gaining more control over what happens in the hardware is a nice bonus, but disabling optimization for no reason just doesn't make sense. The better these optimizations get, the faster we will be able to render accurate images. The thing to remember is that, even when all optimizations are disabled, there are other optimizations going on that we can't touch. ![]()
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