An Energy-Efficient Graphics Processor Featuring Fine-Grain DVFS with Integrated Voltage Regulators, Execution-Unit Turbo, and Retentive Sleep in 14nm Tri-Gate CMOS

Graphics workloads are highly dynamic in nature, using multi-threaded SIMD execution units (EUs), fixed-function units, samplers, and media accelerators to provide ever-increasing amounts of graphics performance. These workloads are often limited by power and thermal constraints, requiring dynamic voltage/frequency scaling (DVFS) of the graphics processor (GPU). This coarse-grain DVFS, driven by a power-management IC (PMIC) setting a shared rail voltage (V IN ), incurs performance loss while waiting for PLL re-lock and slow-rail voltage transitions. In addition, it does not allow a performance-critical unit (e.g. an EU) to use on demand a higher V/F (e.g. for EU turbo) without an energy penalty for the rest of the GPU.