Hierarchical Approximate Memory for Deep Neural Network Applications

Power consumed by a computer memory system can be significantly reduced if a certain level of error is permitted in the data stored in memory. Such an approximate memory approach is viable for use in applications developed using deep neural networks (DNNs) because such applications are typically error-resilient. In this paper, the use of hierarchical approximate memory for DNNs is studied and modeled. Although previous research has focused on approximate memory for specific memory technologies, this work proposes to consider approximate memory for the entire memory hierarchy of a computer system by considering the error budget for a given target application. This paper proposes a system model based on the error budget (amount by which the memory error rate can be permitted to rise to) for a target application and the power usage characteristics of the constituent memory technologies of a memory hierarchy. Using DNN case studies involving SRAM, DRAM, and NAND, this paper shows that the overall memory power consumption can be reduced by up to 43.38% by using the proposed model to optimally divide up the available error budget.