Network Acceleration and Time Synchronization for Data Acquisition Systems using Commodity Networks and Operating Systems

摘要

A user-mode network stack was designed to reduce the network communication latency and jitter of data acquisition and analysis programs. The resulting system has sub-millisecond I/O latency for small message sizes while running on the Microsoft Windows operating system without any custom hardware requirements or application software modifications. Existing applications are transparently redirected to use this custom network stack through the use of replacement dynamic link libraries that intercept standard networking API calls. A software device driver redirects incoming packets into the user-mode stack, allowing accelerated data (specifically, TCP and UDP for IPv4 and IPv6) to bypass the Windows data path. In addition to the user-mode network stack, a network-based software clock with microsecond resolution at the user-mode software level was also produced. This synchronization solution is compatible with Microsoft Windows and the NTPv4 standard, requires no hardware support, and allows clock synchronization to run over a commodity Ethernet network shared with application data, thereby significantly reducing the cost of deployment. The architecture includes a centralized time service, an API that allows access to this time source from all user-mode applications without the delay of a system call, and a device driver that identifies time synchronization packets in the network stack and bypasses key sources of delay in the operating system.