Report Number: CSL-TR-97-731
Institution: Stanford University, Computer Systems Laboratory
Title: A Single Chip Multiprocessor Integrated with High Density DRAM
Author: Yamauchi, Tadaaki
Author: Hammond, Lance
Author: Olukotun, and Kunle
Date: August 1997
Abstract: A microprocessor integrated with DRAM on the same die has the potential to improve system performance by reducing memory latency and improving memory bandwidth. In this paper we evaluate the performance of a single chip multiprocessor integrated with DRAM when the DRAM is organized as on-chip main memory and as on-chip cache. We compare the performance of this architecture with that of a more conventional chip which only has SRAM-based on-chip cache. The DRAM-based architecture with four processors outperforms the SRAM-based architecture on floating point applications which are effectively parallelized and have large working sets.This performance difference is significantly better than that possible in a uniprocessor DRAM-based architecture, which performs only slightly faster than an SRAM-based architecture on the same applications. In addition, on multiprogrammed workloads, in which independent processes are assigned to every processor in a single chip multiprocessor,the large bandwidth of on-chip DRAM can handle the inter-access contention better. These results demonstrate that a multiprocessor takes better advantage of the large bandwidt provided by the on-chip DRAM than a uniprocessor.