基准测试，在虚拟机上进行性能分析 [英] Benchmarking, Profiling on Virtual Machines

问题描述

在许多不同的来源上，您都可以了解有关虚拟机中的计时问题.由于每个基准测试都依赖于时间保持，因此我不确定如何解释例如apache基准测试或xdebug分析器在vmware上的结果以及它们的可信度.

On many different sources you can read about time keeping issues in virtual machines. As every benchmark relies on time keeping i am not sure how to interpret e.g. apache benchmark or xdebug profiler results on vmware and how credible they are.

http://communities.vmware.com/docs/DOC-5581

VMware建议为性能测试构建一个特殊的虚拟机.此外，还有许多技巧似乎是解决方法(安装VMware Tools，特殊配置等).

VMware suggests to build a special vm for performance testing. There are many tips in addition which seems to be workaround solutions (install VMware Tools, special configuration and so on).

尤其是在磁盘I/O性能问题上，我非常担心结果的准确性. Rasmus Lerdorf在drupalcon上谈到了这一点，并说他在统计调用方面的一些性能改进在他的VMware基准测试中是不可见的，因为VMware具有特殊的磁盘缓存，您无法与物理磁盘进行比较:

Especially when it comes to disk i/o performance issues i´m very concerned about how accurate the results are. Rasmus Lerdorf talked about it at drupalcon, saying that some of his performance improvements regarding stat calls aren´t visible in his VMware benchmarks because VMware has special disk caching you can´t compare to physical disks:

http://www. nowpublic.com/tech-biz/rasmus-lerdorf-simple-hard-drupalcon-2008-key-note

毕竟，我不确定VMware是否完全可以进行任何基准测试.

After all this I´m not sure if VMware is capable for any benchmarking at all.

推荐答案

很大程度上取决于您要执行的操作.

A lot depends on what you are trying to do.

1. 只需保持测量以寻找回归
2. 查找可以修复的时差，以提高性能

许多人认为这些是相同的，但我认为这是由于实际操作的经验有限(2).

Many people think these are the same, but I think that comes from limited experience actually doing (2).

我做的方式(2)不是衡量，而是在几个随机的时间点询问正在发生什么以及为什么. 为此，是否在虚拟机上并不重要. 如果它要花很多时间进行偷偷摸摸的事情，您将看到它是否在虚拟机上. 确切的分数无关紧要.揭露偷偷摸摸的活动很重要.

The way I do (2) is not measuring, but asking, at a few random points in time, what is happening and why. For that, it doesn't matter very much if it's on a virtual machine or not. If it's doing something sneaky that takes a large fraction of time, you will see that whether or not it's on a virtual machine. The exact fraction doesn't matter. Exposing the sneaky activity is what matters.

这是一个 Python中的示例，但是您可以使用任何语言进行操作.

Here's an example in python, but you can do it in any language.

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