Catalyst: GPU-assisted rapid memory deduplication in virtualization environments

Content based page sharing techniques improve memory efficiency in virtualized systems by identifying and merging identical pages. Kernel Same-page Merging (KSM), a Linux kernel utility for page sharing, sequentially scans memory pages of virtual machines to deduplicate pages. Sequential scanning of pages has several undesirable side effects---wasted CPU cycles when no sharing opportunities exist, and rate of discovery of sharing being dependent on the scanning rate and corresponding CPU availability. In this work, we exploit presence of GPUs on modern systems to enable rapid memory sharing through targeted scanning of pages. Our solution, Catalyst, works in two phases, the first where pages of virtual machines are processed by the GPU to identify likely pages for sharing and a second phase that performs page-level similarity checks on a targeted set of shareable pages. Opportunistic usage of the GPU to produce sharing hints enables rapid and low-overhead duplicate detection, and sharing of memory pages in virtualization environments. We evaluate Catalyst against various benchmarks and workloads to demonstrate that Catalyst can achieve higher memory sharing in lesser time compared to different scan rate configurations of KSM, at lower or comparable compute costs.