Network

评估网络的五个指标

• 带宽(Bandwidth)：最大吞吐量
• 吞吐量(Throughput)：实际吞吐量
• 延迟(Latency)：发送方和接收方传输和解码的时间
• 抖动(Jitter)：传输中不定期的物理链路不稳定
• 丢包率(Error rate)：传输中错误/丢失的数据比率

Iperf

# rpm -ivh https://iperf.fr/download/fedora/iperf-2.0.1-1.2.el4.rf.x86_64.rpm

带宽

服务器端运行

Server# iperf -s
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 85.3 KByte (default)
------------------------------------------------------------
[  4] local 192.168.2.30 port 5001 connected with 192.168.2.20 port 38317
[  4]  0.0-10.0 sec    664 MBytes    557 Mbits/sec

客户端运行

# iperf -c 192.168.2.30
------------------------------------------------------------
Client connecting to 192.168.2.30, TCP port 5001
TCP window size: 23.2 KByte (default)
------------------------------------------------------------
[  3] local 192.168.2.20 port 38317 connected with 192.168.2.30 port 5001
[  3]  0.0-10.0 sec    664 MBytes    557 Mbits/sec

Server端修改有关TCP窗口内核参数

Server# echo 'net.core.wmem_max=4194304' >> /etc/sysctl.conf 
Server# echo 'net.core.rmem_max=12582912' >> /etc/sysctl.conf 
Server# echo 'net.ipv4.tcp_rmem = 4096 87380 4194304' >> /etc/sysctl.conf 
Server# echo 'net.ipv4.tcp_wmem = 4096 87380 4194304' >> /etc/sysctl.conf 
Server# sysctl -p

服务器端

[root@Da ~]# iperf -s
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 85.3 KByte (default)
------------------------------------------------------------
[  5] local 192.168.2.30 port 5001 connected with 192.168.2.20 port 38320
[  5]  0.0-10.0 sec    807 MBytes    677 Mbits/sec

客户端

# iperf -c 192.168.2.30 
------------------------------------------------------------
Client connecting to 192.168.2.30, TCP port 5001
TCP window size: 23.2 KByte (default)
------------------------------------------------------------
[  3] local 192.168.2.20 port 38320 connected with 192.168.2.30 port 5001
[  3]  0.0-10.0 sec    807 MBytes    677 Mbits/sec

可以看到TCP滑动窗口对性能的影响非常大，从每秒69M提升到每秒84M，啧啧~