Vulkan-Sim: A GPU Architecture Simulator for Ray Tracing

This artifact contains source code for Vulkan-Sim, our MICRO 2022 conference paper. It has detailed instructions on how to generate traces from an example Vulkan application and how to replay the generated traces with Vulkan-Sim's trace runner. Ray tracing can generate photorealistic images with more convincing visual effects compared to rasterization. Recent hardware advances have pushed for the technique to be applied in real-time. Current consumer GPUs feature a dedicated ray tracing acceleration unit, and video game developers have started to make use of ray tracing APIs to bring more realistic graphics to their players. Vulkan features an open-standard API for ray tracing with cross-platform access to modern GPUs. Industry leaders have cooperatively contributed to Vulkan, setting the standard for real-time ray tracing. In this paper, we introduce Vulkan-Sim, a detailed cycle-level simulator for studying Vulkan ray tracing workloads. We build upon the existing GPGPU-Sim simulator, integrating it with Mesa, an open source graphics driver, and add dedicated ray traversal and intersection units. We evaluate several ray tracing workloads with Vulkan-Sim, identifying bottlenecks and inefficiencies of the ray tracing hardware we model. Based on these findings, we also explore a technique of coalescing function calls and independent thread scheduling to alleviate warp divergence and low SIMD efficiency