系统调优
概述
内核参数、文件系统、网络优化技能。
内核参数调优
内存管理
/etc/sysctl.d/99-memory.conf
减少交换倾向
vm.swappiness = 10
脏页刷新
vm.dirty_ratio = 20 vm.dirty_background_ratio = 5
内存过量提交
vm.overcommit_memory = 1 vm.overcommit_ratio = 80
最大内存映射数
vm.max_map_count = 262144
应用
sysctl -p /etc/sysctl.d/99-memory.conf
网络调优
/etc/sysctl.d/99-network.conf
TCP 缓冲区
net.core.rmem_max = 16777216 net.core.wmem_max = 16777216 net.ipv4.tcp_rmem = 4096 87380 16777216 net.ipv4.tcp_wmem = 4096 65536 16777216
连接队列
net.core.somaxconn = 65535 net.core.netdev_max_backlog = 65535 net.ipv4.tcp_max_syn_backlog = 65535
TIME_WAIT
net.ipv4.tcp_tw_reuse = 1 net.ipv4.tcp_fin_timeout = 30 net.ipv4.tcp_max_tw_buckets = 65535
端口范围
net.ipv4.ip_local_port_range = 1024 65535
Keep-Alive
net.ipv4.tcp_keepalive_time = 600 net.ipv4.tcp_keepalive_intvl = 30 net.ipv4.tcp_keepalive_probes = 3
文件系统
/etc/sysctl.d/99-fs.conf
文件句柄
fs.file-max = 2097152 fs.nr_open = 2097152
inotify
fs.inotify.max_user_watches = 524288 fs.inotify.max_user_instances = 512
文件描述符限制
ulimit 配置
/etc/security/limits.conf
- soft nofile 65535
- hard nofile 65535
- soft nproc 65535
- hard nproc 65535
root soft nofile 65535 root hard nofile 65535
systemd 服务
/etc/systemd/system/myapp.service.d/limits.conf
[Service] LimitNOFILE=65535 LimitNPROC=65535
磁盘 IO 调优
IO 调度器
查看当前调度器
cat /sys/block/sda/queue/scheduler
设置调度器
echo deadline > /sys/block/sda/queue/scheduler echo noop > /sys/block/sda/queue/scheduler # SSD echo mq-deadline > /sys/block/nvme0n1/queue/scheduler
永久设置 (GRUB)
GRUB_CMDLINE_LINUX="elevator=deadline"
预读设置
查看预读
blockdev --getra /dev/sda
设置预读 (KB)
blockdev --setra 4096 /dev/sda
挂载选项
/etc/fstab
SSD 优化
/dev/sda1 /data ext4 defaults,noatime,nodiratime,discard 0 2
数据库优化
/dev/sdb1 /mysql ext4 defaults,noatime,barrier=0 0 2
CPU 调优
CPU 频率
查看调速器
cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
设置性能模式
cpupower frequency-set -g performance
或直接设置
echo performance | tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor
NUMA 优化
查看 NUMA 信息
numactl --hardware numastat
绑定 NUMA 节点
numactl --cpunodebind=0 --membind=0 ./program
查看进程 NUMA 分布
numastat -p PID
CPU 亲和性
查看亲和性
taskset -p PID
设置亲和性
taskset -c 0-3 ./program taskset -pc 0-3 PID
常见场景
场景 1：Web 服务器优化
/etc/sysctl.d/99-web.conf
net.core.somaxconn = 65535 net.ipv4.tcp_max_syn_backlog = 65535 net.ipv4.tcp_tw_reuse = 1 net.ipv4.tcp_fin_timeout = 30 net.core.netdev_max_backlog = 65535
文件描述符
fs.file-max = 2097152
场景 2：数据库服务器优化
/etc/sysctl.d/99-database.conf
vm.swappiness = 1 vm.dirty_ratio = 40 vm.dirty_background_ratio = 10 vm.overcommit_memory = 1
大页内存
vm.nr_hugepages = 1024
场景 3：高并发优化
#!/bin/bash
一键优化脚本
网络
sysctl -w net.core.somaxconn=65535 sysctl -w net.ipv4.tcp_max_syn_backlog=65535 sysctl -w net.ipv4.ip_local_port_range="1024 65535"
文件
sysctl -w fs.file-max=2097152
内存
sysctl -w vm.swappiness=10
调优检查
项目 检查命令
文件限制 ulimit -n
网络参数 sysctl -a | grep net
内存参数 sysctl -a | grep vm
IO 调度 cat /sys/block/*/queue/scheduler
故障排查
检查当前限制
cat /proc/PID/limits
检查打开文件数
ls /proc/PID/fd | wc -l lsof -p PID | wc -l
检查网络连接
ss -s netstat -an | awk '/tcp/ {print $6}' | sort | uniq -c