Linux開機時間加速之研究

因各家Linux Distribution，無法預知每位使用者電腦的規格、需求與環境，所以必須在安裝過程時，安裝非常多的套件及啟動大多數的服務，並且執行制式化的RC Script。但這些步驟，對於想要客製化系統的使用者來說這些都是非必要的。消費者往往對產品的第一印象就是產品啟動的時間，使用者只想盡快使用該產品的功能。在本篇論文中，我們先使用Bootchart來分析開機時間，這是一個將開機時的CPU、IO、Process等資訊畫成一張圖表標示出時間座標的工具。我們一開始先分析開機流程，找出其中消耗最多時間的部分，研究該部份的工作原理與前後關係加以修改，並且在盡量不影響功能完整性下，製作出更精簡的開機程序。在最後的實驗結果裡顯示，我們已經可以確定Fedora在Pentium 4主機上，經由我們提出的最佳化方法，整體開機時間由原本的48秒大幅減少到25秒，節省了將盡快要一半的時間，並且也多出許多記憶體空間。雖然這次的實驗平台只有在x86主機上做測試，但以相同的理論與技巧，在未來，我相信可以很輕易的在其他平台上實現加速開機時間的目的。

關鍵字

啟動；加速；開機；裝置檔

並列摘要

Due to different types of Linux Distributions, and unspecified computer specifications, needs and environments of users, it is needed to install many suites, activate most of the services, and execute the default RC Script in each computer. In fact, these steps are unnecessary for users who want a customized system. Consumers’ first impression on the product is usually the time it takes to start up the system, since they want to try out the functions as soon as possible. This thesis first employed Bootchart to analyze the startup time. Bootchart is a tool that plots information, such as CPU, IO, and Processes, to a chart that displays time coordinates. Then, the procedures of startup were analyzed, and the most time-consuming part of the startup procedure was identified in order to study its functioning principles and its relationships with other procedures. This allows us to produce a simpler startup procedure without affecting the full functions. Results of the experiment suggested that the proposed optimization method applied on the Fedora of Pentium 4 can reduce the startup time from 48 to 25 sec, which saved almost half of the time and increased the free memory space. Although the experiment was only conducted on x86 host, identical theories and techniques could be conducted on other hosts to speed up the startup time in other platforms.