GISP: A Transparent Superpage Support Framework for Linux

Though all of the current main-stream OSs have supported superpage to some extent, most of them need runtime information provided by applications, simulator or other tools. Transparent superpage support is a further step, while so far there are only very few primitive attempts for Linux. In this paper, we propose the design of GISP (global information based super page support), a transparent superpage support framework in Linux kernel. GISP adopts the basic idea of the reservation-based policy, and uses LMO (lightweight memory object) and POPMAP (population map) to manage the page allocation for applications. GISP could provide the core functions of superpage support while keeping the memory continuity by dynamic pages recycling. We implement it in Linux 2.4.17 on PKUnity SoC, and evaluate it for real workloads and benchmarks. We obtain substantial performance benefits from 8.1% to 24.0%. Compared with the best transparent superpage support in Linux up to now, we achieve better performance from 0.4% to 4.6% in most cases; even the worst case has comparable performance improvements within 2.6%. Otherwise, it keeps low management cost during system running which is suitable for not only scientific applications but also commodity applications.