Texturing performance
We measured performance during access to textures of different formats in bilinear filtering. Here are the results for standard 32-bit (4xINT8), 64-bit “HDR” (4x FP16) and 128-bit (4x FP32). We have also added performance for 32-bit RGB9E5, a new HDR format introduced in DirectX 10 which allows 32-bit HDR textures to be stocked, give or take a few compromises.
As announced by NVIDIA, the GeForce GTX 500s can filter FP16/11/10 and RGB9E textures at full speed and give 2.35x and 2.58x better performance in comparison with the GeForce GTX 480 and 470.
The filtering power of the Radeon HD 6900s is so far superior however that even though they have to filter FP16 textures at half speed, they aren’t too far behind the GeForces.
Note that we had to raise the energy consumption limit of the Radeon HD 6900s to the max, as otherwise clocks were reduced in this test. These new Radeons seem, then, incapable of fully using all their texturing power by default!
Fillrate
We measured the fillrate without and then with blending, and this with different data formats:
In terms of fillrate, the Radeons have a big advantage over the GeForce GTX 400s/500s, above all with FP10s, a format processed at full speed while with the GeForces this format is processed at half-speed. Given the limitation of the GeForces in terms of datapaths between the SMs and ROPs, it’s a shame that NVIDIA hasn’t given its GPU the possibility of benefitting from FP10 and FP11 formats.
Like the GeForces, the Radeon HD 6900s can process FP32 single channel at full speed without blending, but retain this speed with blending.
