参考文档：https://plantegg.github.io/2019/09/28/%E5%B0%B1%E6%98%AF%E8%A6%81%E4%BD%A0%E6%87%82TCP–%E6%80%A7%E8%83%BD%E5%92%8C%E5%8F%91%E9%80%81%E6%8E%A5%E6%94%B6Buffer%E7%9A%84%E5%85%B3%E7%B3%BB/
https://plantegg.github.io/2016/08/24/Linux%20tc%20qdisc%E7%9A%84%E4%BD%BF%E7%94%A8%E6%A1%88%E4%BE%8B/
基本概念
QPS和RT
QPS： query per second，is a measure of the amount of search traffic an information-retrieval system, such as a search engine or a database, receives in one second.[1]
RT： response time,一个请求完成的时间
Little’s law
that the long-term average number L of customers in a stationary system is equal to the long-term average effective arrival rate λ multiplied by the average time W that a customer spends in the system. Expressed algebraically the law is
A very brief example is that, one university admit 2000 students per year, and all students need to study 4 years, then whenever the university has 2000*4 = 8000 students.
实验步骤
server side：
- generate 2G file：
fallocate -l 2G haiming - start monitoring by
tcpdump:tcpdump -s 120 -w server.pcap - start one simple http server on port 8089:
python3 -m http.server 8089
client side:
- try ping
google.com:ping google.com - start tcpdump:
tcpdump -s 120 -w client.pcap - get the big 2G file:
curl 172.31.24.234:8089/haiming --output ~/haiming - try ping
google.com:ping google.com
