GPUart - An application-based limited preemptive GPU real-time scheduler for embedded systems

摘要

Emerging technologies like autonomous driving entail computational intense software solutions. More and more companies accelerate their embedded applications by General Purpose Computing on the Graphics Processing Unit (GPGPU), in order to overcome those computational demands. Unfortunately, Graphics Processing Units (GPUs) severely lack real-time capability, for example controllable preemption support, which limits their applicability in the embedded domain. We therefore present GPUart, a framework for GPU real-time scheduling. GPUart focuses on embedded systems and requires neither hardware nor driver stack extensions. We propose a software-only approach for preemption, based on the fixed preemption point strategy. In contrast to prior work, GPUart enables preemption inside a thread block by adding fixed preemption points. We further propose a portable high-level resource management concept to enable gang scheduling on GPUs. GPUart can schedule GPU workload either under the Gang-Earliest Deadline First (EDF) or Gang-Fixed Task Priority (FTP) policy. A case-study on Nvidia Tegra X1, using real-world engine management applications from Audi AG and Continental Automotive GmbH, shows that only up to 0.28% additional global memory is required to enable interruptible thread blocks. GPUart reduces the worst observed response times by a factor of up to 221, leading to response times without deadline misses.