NDPmulator: Enabling Full-System Simulation for Near-Data Accelerators From Caches to DRAM

The accurate simulation and performance assessment of Near-Data Accelerators (NDAccs) is a complex challenge as it must consider the operation of the entire processing system, the impact of the Operating System (OS) overheads, and the memory contention caused by concurrent processes. While recent proposals have attempted to repurpose and extend existing tools, the offered support for the development and evaluation of NDAccs is limited and full-system simulation is rarely provided. To mitigate this problem, the NDPmulator simulation framework, based on the widely established gem5 architectural simulator, is herein proposed. NDPmulator provides System Emulation (SE) and Full System (FS) support for the development and evaluation of novel NDAccs deployed at multiple levels of the memory hierarchy. To demonstrate its versatility and performance-efficiency, the proposed NDPmulator is used to model three existing NDAccs, showing that it can accurately estimate and anticipate the results of the evaluation performed by the original authors while requiring a significantly smaller implementation effort and a fraction of the simulation time. Furthermore, NDPmulator offers the possibility to conduct complex experiments where the NDAcc is coupled to a real system featuring an OS. Hence it allows modeling all overheads related to the NDAcc device driver, the OS, and the contention caused by concurrent and background processes.