Dolunay: Architectural Support for Independent Thread Scheduling in a RISC-V SIMT Accelerator
Single-Instruction Multiple-Thread (SIMT) architectures have revolutionized data-parallel computing by providing a high-throughput abstraction that simplifies vector management. However, traditional stack-based SIMT models do not support intra-warp synchronization primitives such as mutexes and spin-locks. This work introduces Dolunay, a RISC-V-based Independent Thread Scheduling (ITS) SIMT accelerator. By only adding three custom instructions, Dolunay employs a cooperative multitasking model and explicit synchronization barriers at the hardware-level, and provides the forward-progress guarantees necessary to implement starvation-free algorithms. We evaluate Dolunay on the Cmod A7-35T FPGA module and demonstrate its ability to correctly execute kernels that deadlock on traditional stack-based architectures while still achieving parallel execution for conventional compute-heavy kernels.