[转]Monitoring and Tuning the Linux Networking Stack: Receiving Data

最近在网上看到了一篇详细介绍Linux系统上接收网络数据包过程的博客（英文的），觉得很不错，特地分享一下。如果你想做Linux的网络性能优化，这是一篇很好的参考文章。

The networking stack is complex and there is no one size fits all solution. If the performance and health of your networking is critical to you or your business, you will have no choice but to invest a considerable amount of time, effort, and money into understanding how the various parts of the system interact.

Ideally, you should consider measuring packet drops at each layer of the network stack. That way you can determine and narrow down which component needs to be tuned.

This is where, I think, many operators go off track: the assumption is made that a set of sysctl settings or /proc values can simply be reused wholesale. In some cases, perhaps, but it turns out that the entire system is so nuanced and intertwined that if you desire to have meaningful monitoring or tuning, you must strive to understand how the system functions at a deep level. Otherwise, you can simply use the default settings, which should be good enough until further optimization (and the required investment to deduce those settings) is necessary.

Many of the example settings provided in this blog post are used solely for illustrative purposes and are not a recommendation for or against a certain configuration or default setting. Before adjusting any setting, you should develop a frame of reference around what you need to be monitoring to notice a meaningful change.

Adjusting networking settings while connected to the machine over a network is dangerous; you could very easily lock yourself out or completely take out your networking. Do not adjust these settings on production machines; instead make adjustments on new machines and rotate them into production, if possible.

https://blog.packagecloud.io/eng/2016/06/22/monitoring-tuning-linux-networking-stack-receiving-data/

还有一篇图示简化版的，适合没有时间的朋友……

https://blog.packagecloud.io/eng/2016/10/11/monitoring-tuning-linux-networking-stack-receiving-data-illustrated/