> For the complete documentation index, see [llms.txt](https://book.bsdcn.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://book.bsdcn.org/life/di-si-bu-fen-unix-zhi-wai/10.-unix-fu-wu/10.1.-ji-zhun-ce-shi.md).

# 10.1 基准测试

> “有谎言，有该死的谎言，然后还有基准测试。”—— 佚名

人们用基准测试来评判不同程序（或机器、操作系统等）的优劣，依据是完成同一件工作所需时间的长短（或者空间、价格等）。基准测试常常沦为笑柄，因为它们往往被拿来当作无效外推的根据，得出的结论离谱至极、误导性十足。不过，明智地使用基准测试也是可能的，比如用它来做系统调优。

据说有些系统认得出自己正在运行基准测试，于是直接打印出一个预先算好的答案。这种事虽然让人难以置信，但优秀的优化器的本事，已经足以删掉大多数基准测试中通常占相当比重的死代码，从而让基准测试设计者的意图落空。无论如何，对基准测试都要保持高度警惕。要检验系统的吞吐量，现实得多的做法是坐到系统跟前，试着运行几个你自己的应用程序。别忘了确认它的内存容量与你中意的那台系统相当，速度、磁盘和网络也与之相同。（典型的展厅样机都插满了内存，配着高速磁盘。）

你若是执意无视我们的警告，卖基准测试的公司有的是。其中比较知名的有：Aim Technology、Neal Nelson & Associates 和 Performance Awareness。不言而喻，对 UNIX 厂商自己拿出的基准测试，你尤其要多加提防。

关于 UNIX 基准测试，有几篇不错的读物：“The Evolution of UNIX System Performance”，作者 J. Feder，载于 AT\&T Bell Laboratories Technical Journal 第 63 卷第 8 期，1984 年 10 月；“Benchmark Confessions”，作者 P. Marvit 和 M. Nair，载于 The UNIX System – Encyclopaedia，Yates Ventures，1984 年；以及“Benchmarking UNIX Systems”，作者 D. Hinnant，载于 BYTE Magazine 第 9 卷第 8 期，1984 年 8 月。


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