ATI PowerPlay Reanalyzed
While all the power testing details and PowerPlay options were shared in our original performance article, we will simply recap on some of the highlights today. The easiest way to configure ATI's PowerPlay for Linux is through using the aticonfig utility. To specify the power-state immediately, as well as writing to your X.Org configuration (if write permissions allowed), is through aticonfig --set-powerstate=<VALUE>. In order to see the various power-states prior to applying them, they can be listed through the aticonfig --lsp option. For reference, below are the available power-states using the Mobility RADEON X300. These power-states vary depending upon the GPU. ATI's technical documentation states that PowerPlay is a hybrid of hardware and software, and is compatible with the Radeon 9000 series and later.
$ aticonfig --lsp core/mem [flags] --------------- 1: 105/122 MHz [low voltage] 2: 209/182 MHz [low voltage] 3: 297/230 MHz [default state]
With the original PowerPlay examination, we had examined the power consumption as it was running off the battery. For this article, we monitored the power consumption when running off the charger, and then again when it was running off the IBM battery. This was done due to differences in the power management when running off the battery and then again the AC adapter. A SeaSonic PowerAngel was used to monitor the Wattage from the AC adapter, while the Linux ACPI functions were used with the battery. For those not familiar with Advanced Configuration and Power Interface (ACPI) Linux, /proc/acpi/battery/BAT0/state does display the charging/discharging rate as well as other pertinent information. Meanwhile, /proc/acpi/battery/BAT0/info displays other battery information. Below are two sample outputs.
$ cat /proc/acpi/battery/BAT0/state present: yes capacity state: ok charging state: discharging present rate: 19845 mW remaining capacity: 18950 mWh present voltage: 11124 mV $ cat /proc/acpi/battery/BAT0/info present: yes design capacity: 47520 mWh last full capacity: 44540 mWh battery technology: rechargeable design voltage: 10800 mV design capacity warning: 2227 mWh design capacity low: 200 mWh capacity granularity 1: 1 mWh capacity granularity 2: 1 mWh model number: IBM-92P1075 serial number: 2800 battery type: LION OEM info: SANYO
Having the battery monitoring covered, we monitored the effects of PowerPlay on the frame-rate performance using fgl_glxgears and RTCW: Enemy Territory v2.60. We monitored the average frame-rate with fgl_glxgears and used the Railgun time-demo for Enemy Territory. Finally onto the results, on the following pages is our recorded power consumption from running off the battery and again with the AC power supply, as well as the frame-rate tests. The power monitoring had occurred while idling inside of GNOME with no applications running and the screen-saver disabled. We had also monitored the Wattage when fgl_glxgears was running. Each of these tests was carried out at the three available power-states for the ATI Mobility X300 and the v8.24.8 drivers.