Linux系统运维

内核参数

tcp_max_tw_buckets

这个参数52w太大了，导致同样的业务流量下，机器负载明现偏高

# 查看方式
sysctl -a | grep "tcp_max"
cat /proc/sys/net/ipv4/tcp_max_tw_buckets

# 值
net.ipv4.tcp_max_tw_buckets = 524288
net.ipv4.tcp_max_tw_buckets = 16384

txqueuelen

# 设置
ifconfig eth1 txqueuelen 10000
echo "ifconfig eth1 txqueuelen 10000" >> /etc/rc.d/rc.local

somaxconn

tcp的accept队列长度=min(somaxconn, backlog)

# 查看方式
sysctl -a | grep "net.core.somaxconn"
cat /proc/sys/net/core/somaxconn

# 设置
echo 4096 > /proc/sys/net/core/somaxconn
在/etc/sysctl.conf中添加: net.core.somaxconn = 4096

命令

1. 查看登录用户

cat /var/log/secure | grep Accept

设置hostname

echo "kernel.hostname = hostname_temp_test" >> /etc/sysctl.d/hostname.conf
sysctl -p /etc/sysctl.d/hostname.conf

sed -i "1s/$/ hostname_temp_test/" /etc/hosts
echo "NETWORKING=yes" >> /etc/sysconfig/network

2. 统计目录下文件行数

Reference: https://www.cnblogs.com/phpfans/p/4474624.html

# 统计目录下所有文件行数
find . -type f | xargs cat | wc -l

# 统计目录下所有C代码行数
find ./ -name "*.c" | xargs cat | grep -v ^$ | wc -l

# 查看目录下各C代码文件行数
for i in `find ./ -name "*.c"`; do cat | wc -l $i; done;

3. iptables

# 多个端口
iptables -I ETH1_TCP -p tcp -m multiport --dports 8848,8849 -s 0.0.0.0/0 -j ACCEPT

4. curl

# 忽略证书
curl -k

# -H "Host:xxx"
curl -v -H "Host:www.baidu.com" "http://0.0.0.0/hls/10086_666.m3u8"


curl -v https://yun.playauth.live.qcloud.com/fdsaaa?abcccc
tcpdump -i eth1 -n -A  port 8848 | fgrep abccc

5. nc验端口

# 监听端口
nc -ul port
# 连接
nc -u ip  port 
# 然后互发数据测试下

6. cpu

Reference:

# 物理CPU个数
cat /proc/cpuinfo | grep "physical id" | sort | uniq | wc -l
# 单个CPU的核数
cat /proc/cpuinfo | grep "cpu cores"| uniq
# 逻辑CPU个数
cat /proc/cpuinfo |grep "processor" | wc -l 

7. top

8. 网卡

Reference: https://www.cnblogs.com/zengkefu/p/5583618.html

ethtool eth0

# QDisc(queueing discipline)
# 设置大小
ifconfig eth1 txqueuelen 10000
echo "ifconfig eth1 txqueuelen 10000" >> /etc/rc.d/rc.local
# 查看丢包
tc -s qdisc show
执行结果: 
qdisc mq 0: dev eth1 root 
 Sent 7857971645 bytes 47398281 pkt (dropped 0, overlimits 0 requeues 0) 
 backlog 0b 0p requeues 0 

9. 系统启动相关

# 启动时的相关配置
chkconfig --list | grep 3:on
# 重启记录
last | grep reboot

 

 

qdisc

kmalloc/vmalloc/malloc

slab/slub/slob

Reference: https://blog.csdn.net/lukuen/article/details/6935068