Ultrafork and Focused KSM: Tools for Memory Optimization in Duplicate Containers

Simoneau, Alexander; Curless, Adrian; Cross, William

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Ultrafork and Focused KSM: Tools for Memory Optimization in Duplicate Containers

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Containers are an increasingly common tool for providing isolation between applications running on the same hardware. Increased isolation provides protection from attacks at the cost of increased memory usage. Common memory sharing techniques such as page sharing and deduplication do not work well across container boundaries. This work presents two tools for sharing memory between containers, Ultrafork and Focused KSM. Ultrafork provides a way to clone containers in a similar manner to how fork clones processes. The cloned containers share memory copy-on-write with the original container, preventing need-less copying when containers start. Focused KSM provides an implementation of Kernel Same-Page Merging specific to containers. It is able to merge duplicate pages while containers are running. Together, Ultrafork and Focused KSM provide robust and effective memory optimization for containers. We show that significant memory savings can be achieved with only a small CPU overhead.

This report represents the work of one or more WPI undergraduate students submitted to the faculty as evidence of completion of a degree requirement. WPI routinely publishes these reports on its website without editorial or peer review.

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