Power Management: ATI Catalyst vs. Open-Source ATI Driver

When firing up Tremulous on the ThinkPad T60 with the open-source driver, the average power consumption was 23,441 Milliwatts and the range was from 20,185 to 25,150.

While by a slimmer margin, the Catalyst driver consumed more power than the open-source stack when the Mobility X1400 GPU was under OpenGL load. The average battery power consumption was 23596 Milliwatts. The difference between the two averages though is just 155 Milliwatts. The power consumption peaked at 24522 Milliwatts, which is over 600 Milliwatts less than its open-source alternative. The power consumption bottomed out at 20112 Milliwatts, which is also less.

From these quick tests, the system's battery power consumption between the Catalyst driver and xf86-video-ati + Mesa driver is quite close -- at least with the ATI Mobility Radeon X1400 found on the Lenovo ThinkPad T60. What is important to reiterate, however, is that each driver was left at its defaults. Had we manually lowered the PowerPlay state, which reduces the frequencies that the GPU operates at along with its voltage, we would have certainly seen a lower power consumption, but at a lower frame-rate. The PowerPlay states can be controlled through the aticonfig utility.

The open-source ATI stack will most certainly improve when it comes to graphics power management. In fact, it has already begun to since the release of Ubuntu 8.10 and the packages we tested. There is the basic PowerPlay support for the R500 series plus work being done by Red Hat to improve GPU power management. Among the areas being focused on are clock-gating, GPU core re-clocking, frame-buffer compression, memory re-clocking, shutting down unused PLLs, and LVDS re-clocking are among the areas. We will likely see other areas being worked on as well over the next few months.

Stay tuned to Phoronix for more information on ATI Linux changes. Discuss these changes in the Phoronix Forums.