Zebra Refresh: Value Transformation for Zero-Aware DRAM Refresh Reduction

Abstract

Refresh operations consume growing portions of DRAM power with increasing DRAM capacity. To reduce the power consumption of such refresh operations, this paper proposes a novel value-aware refresh reduction technique exploiting the abundance of zero values in the memory contents. The proposed Zebra refresh architecture transforms the value and mapping of DRAM data to increase consecutive zero values, and skips a refresh operation for a row containing zero values entirely. Zebra converts memory blocks to base and delta values, inspired by a prior compression technique. Once values are converted, bits are transposed to place consecutive zeros matching the refresh granularity. The experimental results show Zebra refresh can reduce DRAM refresh operations by 43 percent on average for a set of benchmark applications.