"Turning the Page" on Hugetlb Interfaces

HugeTLBFS was devised to meet the needs of large database users. Applications use filesystem calls to explicitly request superpages. This interface has been extended over time to meet the needs of new users, leading to increased complexity and misunderstood semantics. For these reasons, hugeTLBFS is unsuitable for potential users like HPC, embedded, and the desktop. This paper will introduce a new interface abstraction for superpages, enabling multiple interfaces to coexist, each with separate semantics.

To begin, a basic introduction to virtual memory and how page size can affect performance is described. Next, the differing semantic properties of common memory object types will be discussed with a focus on how those differences relate to superpages. A brief history of hugeTLBFS and an overview of its design is presented, followed by an explanation of some of its problems. Next, a new abstraction layer that enables alternative superpage interfaces to be developed is proposed. We describe some extended superpage semantics and a character device that could be used to implement them. The paper concludes with some goals and future work items.


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