Flexible Instruction Set Architecture for Programmable Look-up Table based Processing-in-Memory

Abstract

Processing in Memory (PIM) is a recent novel computing paradigm that is still in its nascent stage of development. Therefore, there has been an observable lack of standardized and modular Instruction Set Architectures (ISA) for the PIM devices. In this work, we present the design of an ISA which is primarily aimed at a recent programmable Look-up Table (LUT) based PIM architecture. Our ISA performs the three major tasks of i) controlling the flow of data between the memory and the PIM units, ii) reprogramming the LUTs to perform various operations required for a particular application, and iii) executing sequential steps of operation within the PIM device. A microcoded architecture of the Controller/Sequencer unit ensures minimum circuit overhead as well as offers programmability to support any custom operation. We provide a case study of CNN inferences, large matrix multiplications, and bitwise computations on the PIM architecture equipped with our ISA and present performance evaluations based on this setup. We also compare the performances with several other PIM architectures.