UBC: An Efficient Unified I/O and Memory Caching Subsystem for NetBSD

This paper introduces UBC ("Unified Buffer Cache"), a design for unifying the filesystem and virtual memory caches of file data, thereby providing increased system performance. In this paper we discuss both the traditional BSD caching interfaces and new UBC interfaces, concentrating on the design decisions that were made as the design progressed. We also discuss the designs used by other operating systems to solve the same problems that UBC solves, with emphasis on the practical implications of the differences between these designs. This project is still in progress, and once completed will be part of a future release of NetBSD.