Mesa R500 Texture Semaphore Improvements
A few different shader-using OpenGL tests were executed via the Phoronix Test Suite, but only with Lightsmark was there a noticeable difference with this texture semaphore work compared to mainline Mesa. The above graph illustrates the tex-sem work on the Radeon X1800XT 256MB graphics card.
Compared to mainline, when the maximum texture look-up count was four or less, it really was not of any benefit over mainline Mesa. However, with RADEON_TEX_GROUP having a value of eight (the current default), there was a definite improvement for this R520 GPU. The Radeon X1800XT performance in Lightsmark improved by 32% with the instruction scheduler work done by Tom Stellard. Setting RADEON_TEX_GROUP to a value greater than eight was of no benefit for Lightsmark on this Radeon GPU.
With the Radeon X1950PRO, the testing carried out was similar, but with a greater number of RADEON_TEX_GROUP tests. Like the X1800XT testing, when RADEON_TEX_GROUP was set to four texture look-ups or less, there was not an improvement. When the value was set to six, the frame-rate went up by 8%. With the default value of eight, the frame-rate went up by 32% in Lightsmark for the RV570 GPU. Any value above eight was of no greater benefit.