The GPU performance state APIs are used to get and set various performance
levels on a per-GPU basis. P-States are GPU active/executing performance
capability and power consumption states.
P-States range from P0 to P15, with P0 being the highest performance/power
state, and P15 being the lowest performance/power state. Each P-State maps to
a performance level. Not all P-States are available on a given system. The
definition of each P-States are currently as follows:
P0/P1 - Maximum 3D performance
P2/P3 - Balanced 3D performance-power
P8 - Basic HD video playback
P10 - DVD playback
P12 - Minimum idle power consumption
