改進UnixWare 2.01上UDP效能以支援多媒體應用程式

Abstract

分散式多媒體應用程式，例如隨選視訊系統和視訊會議系統，經由網路 來傳送連續性視訊資料時，通常需要很高的網路頻寬。近年來，網路硬體 的頻寬已足夠支援這些應用程式於即時性要求下傳送視訊流。然而，網路 軟體的效能卻未隨網路硬體的成長而提昇。換言之，網路軟體限制住了實 際的網路頻寬。為了增進視訊伺服器的能力，網路軟體勢必需要做些改變 或修改。這篇碩士論文，我們專注於 UDP 協定的改進，包括消去 checksum、排除 user-to-kernel 資料拷貝、及記憶體的配置和歸還。結 果顯示，我們提昇了 UDP/IP 通訊協定的整體頻寬達8.33% Distributed multimedia applications, such as video-on-demand (VOD) and video-conferencing, demand high data bandwidth for transferring continuous video datathrough networks. Currently, the bandwidth of modern network hardware is largeenough to support these applications to send video stream in real-time. However, the performance of network software does not increase as fast as that of network hardware. In other word, the network bandwidth is limited by network software. In order to improve the capability of a video server, some changes andmodifications of network software must be made. In this thesis, we focus on the improvement of the UDP protocol. The modifications include checksum elimination,user-to-kernel data copy elimination, and memory allocation and deallocationreduction. As a result, the obtained total bandwidth of UDP/IP can be up to8.33%.