Providing asynchronous file I/O for the Plan 9 operating system

Abstract

This thesis proposes a mux abstraction that multiplexes messages of a network file protocol to provide asynchronous access to all system resources on the Plan 9 operating system. The mux provides an easy-to-program asynchronous interface alleviating the need to manage multiple connections with different servers. A modified version of the Plan 9 Web server demonstrates that the mux can be used to implement a high-performance server with user-level threads without having to use a kernel thread for each user-level thread. Scalability tests demonstrate that the mux implementation scales well with hundreds of clients and hundreds of servers. Furthermore, the user-threaded version of the web server performs comparably with the kernel-threaded implementation on disk bound workloads and exhibits an 18% decrease in performance on in memory workloads. These results suggest that the mux could provide performance benefits for more intricate applications that can exploit the fine-grained control of user-level scheduling.