Analysis: Sampling and Filtering

We've run all our tests at 1920x1200, and we'll also be showing you results for the 5870 at 850E/975M to bring it on equal footing with the 4890 and hopefully outline pure architectural benefits/changes.

The first step is to look at texturing rates for a very simple test case: we use a 2x2 4-channel INT8 texture with point filtering, trying to see if everybody plays nice and hits maximum theoretical rates :

As you can see, everyone hits about 98% of their theoretical rates here (remember, the 4890 has only 32 interpolators, so it's maximum is 27,2 GTexels/s). Next, we'll look at filtering in a slightly more complicated scenario: we take a multi-textured plane and rotate it around origin, varying filtering from Bilinear to 16x Anisotropic, looking to expose the performance curve:

Cypress appears to be slightly better at maintaining its performance up to 16x anisotropic, where it's possible that either the decreased L1 cache size or angle-invariance offset the improvements which seem to be present in the samplers themselves. However, we'll do far more work with filtering in an upcoming piece, so look at this as at most an appetiser, rather than the main course.