Decongest: Accelerating Super-Dense PCM Under Write Disturbance by Hot Page Remapping

Abstract

At small feature sizes, phase change memory (PCM) shows write disturbance (WD) error (WDE) and this issue can eclipse the density and energy efficiency advantage of PCM. We propose ‘Decongest’, a technique to address WD errors in main memory designed with super-dense ( $4F^2$ cell size) PCM. Decongest works by identifying and remapping write-intensive hot pages to a WD-free spare area, which avoids WD to nearby pages due to writing these hot pages, and WD to these hot pages from writing nearby pages. Compared to a WD-affected super-dense PCM baseline, Decongest improves the performance by 14.0 percent, and saves 21.8 percent energy.