Performance Characterisation and Simulation of Intel's Integrated GPU Architecture

Integrated GPUs (iGPUs) are ubiquitous in today's client devices such as laptops and desktops. Examples include Intel's HD or Iris Graphics and AMD's APUs. An iGPU resides on the same chip as the CPU, which is in contrast to a conventional discrete GPU that would typically be connected over the PCI-E bus. Much like discrete GPUs, iGPUs are also capable of general purpose computation in addition to traditional graphics roles. Further, iGPUs have some interesting differences compared to traditional GPUs such as a cache-coherent memory hierarchy and a shared last level cache with the CPU. Despite their wide spread use, they are not studied very extensively. To the best of our knowledge, this paper introduces the first open source trace generation and microarchitectural simulation framework for Intel's integrated GPUs. We characterise the performance of Intel's Skylake and Kabylake GPUs through detailed microbenchmarks, and use the performance evaluations to guide our models and validate the simulator.