Execution Units Power-Gating to Improve Energy Efficiency of GPGPUs

In this paper, we examine the distribution and the length of execution units idle cycles for several typical GPGPU applications to direct the energy-saving strategies to capture potential execution units power-gating opportunities. We record the idle durations of the execution units for SMs (Streaming Multiprocessors) including integer units and floating units in SPs (Streaming Processors) and SFUs (Special Function Units). Second, based on the observation of idleness, we study the effectiveness of the execution units power-gating on the leakage energy saving with two simple policies, the immediate power-gating (IPG) and idle detect power-gating (ID-PG). We examine the polices with various parameter settings in order to offer insights on possible gains and losses from the power-gating techniques to enable smarter strategies in future research. The experimental results show that both policies can achieve satisfactory leakage energy saving on execution units. The immediate power-gating can reduct the execution units leakage energy by 84.3% when the break even time is set to 5 cycles and the idle detect power-gating can save 67.1% of the total execution units leakage energy even if the break even time goes up to 20 cycles.