SCALE DRAM subsystem power analysis

Abstract

To address the needs of the next generation of low-power systems, DDR2 SDRAM offers a number of low-power modes with various performance and power consumption tradeoffs. The SCALE DRAM Subsystem is an energy-aware DRAM system with various system policies that make use of these modes. In this thesis, we design and implement a DDR2 DRAM controller and test a version of the SCALE DRAM Subsystem in hardware. Power measurements from the actual DRAM chips are taken and compared to datasheet derived values, and an analysis of the DRAM refresh requirements is performed. Some notable power consumption results include active powerdown being much closer to precharge powerdown and reads taking much less current than the datasheet indicates. In addition, based on the refresh tests, a system that powers down at least 12.3s for each 32MB of traffic can save power using delayed refresh and ECC data encoding.