Today’s Modern GPUs incorporate advanced mechanisms for power management during active workloads.If parts of Graphics Engine are not fully stressed under a rendering or compute workloads,GPU will work to reduce the power in that part using clock rate and power gating techniques.In the course of full workloads,GPU will be very heavily loaded with workloads that it will have less chance to reduce the clock rates and gate the power.While in some cases,where the GPU depend on the data from the CPU and frame buffer,then using that time to lower the power under loads.
As a Result of this GPU power management under active workloads,it can be demonstrated that the each application having their own power signatures on how particular application uses the graphic architecture and how much opportunity GPU has to reduce the power.
|Figure showing each application including games and benchmark software that how much power they utilize from 225 Discrete GPU|
Measurements from Modern GPUs also shows that there is a small set of peak applications(known as”power viruses”) that consumes higher power when compared to other applications.GPUs has to accommodate that higher power applications has always led to compromise in performance.Any application which will run in long run recursion will trigger a “thermal event”.This event exceeds the value which is already set to the GPU sensors,where the GPU has to take an immediate actions to reduce the voltage power and frequency to keep GPU operate in temperate mode.Thermal event lead to less performance and restricts the opportunity to GPU to move back to high performance Band.
As a result of this compromise,Typical applications that consume less power are not able to use the full power of GPU to maximize the GPU performance within the GPU TDP.
|figure shows GPU loses performance opportunity|
With an intelligent mechanism to manage the clocks in response to active power during workloads,AMD has provided with two Power saving technology on Radeon Cards.
AMD POWERTUNE TECHNOLOGY
AMD addresses this TDP power/performance compromise by introducing two important capabilities to GPUs power management
- The ability for the GPU to dynamically calculate its run time power based on workload activity.
- The intelligence to control engine clocks based on power calculations.
Powertune dynamically manages the graphics engine clock speed based on calculations which determine the GPU to its TDP limit.The ability of PowerTune to calculate how close it is to the TDP delivers significant performance for power constrained applications.Thus PowerTune is significantly higher while comparing to the traditional methods of thermal throttling to the intermediate power states.
As a result , general as well as the power hungry applications will dynamically use the GPU compute power within the product’s TDP limit.
AMD ZEROCORE POWER TECHNOLOGY
This technology works as same as operating system’s sleep mode,but GPUs which continuously refreshing display device from its frame buffer during the static screen operation uses power saving techniques like power gating,clock gating and memory compression.This techniques can be used when there is no display refresh required.
All personal computers are configured to turn off their display after a long period of user activity and lack of input.This state is known as Long Idle State where the screen is blanked but the rest of the system is in active and working power state.when PC reaches this State and applications are not actively using the GPU resources,the GPU enters a state where the power is completely down.However one cannot remove the GPU in this state,because may operational devices cannot function without the GPU as it is logically present in the system.
When the system is powered with more than one AMD Radeon Cards,then this technology will power down all the non-primary GPUs and only primary GPU will be ON in a Long Idle State.However,by completely powering down all the cores,user can still perform non graphical activities such as sharing,streaming,motherboard audio without worrying about the traditional GPU power cost and impact.
Hence,both this technology works in a different way to save the power on the AMD RADEON Cards