As in earlier Addison-Wesley books on the UNIX-based BSD operating system, Kirk McKusick and George Neville-Neil deliver here the most comprehensive, up-to-date, and authoritative technical information on the internal structure of open source FreeBSD. Readers involved in technical and sales support can learn the capabilities and limitations of the system; applications developers can learn effectively and efficiently how to interface to the system; system administrators can learn how to maintain, tune, and configure the system; and systems programmers can learn how to extend, enhance, and interface to the system. The authors provide a concise overview of FreeBSD's design and implementation. Then, while explaining key design decisions, they detail the concepts, data structures, and algorithms used in implementing the systems facilities. As a result, readers can use this book as both a practical reference and an in-depth study of a contemporary, portable, open source operating system. This book: Details the many performance improvements in the virtual memory system Describes the new symmetric multiprocessor support Includes new sections on threads and their scheduling Introduces the new jail facility to ease the hosting of multiple domains Updates information on networking and interprocess communication Already widely used for Internet services and firewalls, high-availability servers, and general timesharing systems, the lean quality of FreeBSD also suits the growing area of embedded systems. Unlike Linux, FreeBSD does not require users to publicize any changes they make to the source code.