121 lines
3.0 KiB
Markdown
121 lines
3.0 KiB
Markdown
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# 设备TCP栈调优操作记录
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> **目标**：根据本地带宽动态调整TCP接收/发送缓冲区，使其能容纳带宽延迟积（BDP）。
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## 1. 环境信息收集
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### 1.1 基础硬件与系统信息
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```bash
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# 设备型号
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cat /tmp/sysinfo/model
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# 内核版本
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uname -r
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# 总内存
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grep MemTotal /proc/meminfo
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```
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### 1.2 当前TCP参数快照
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```bash
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sysctl net.ipv4.tcp_rmem \
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net.ipv4.tcp_wmem \
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net.core.rmem_max \
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net.core.wmem_max \
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net.ipv4.tcp_congestion_control \
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net.core.netdev_max_backlog
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```
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### 1.3 网络链路与带宽测试
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- **查看WAN口速率**（替换`<wan口>`为实际接口名，如`eth0`）：
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```bash
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ethtool <wan口> | grep -i speed
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```
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- **实测带宽**（确保无代理干扰）：
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```bash
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# 检查代理进程
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ps | grep -E "openclash|mihomo"
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# 若存在代理，请先关闭；然后测速
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speedtest --accept-license --format=json
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```
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### 1.4 检查BBR拥塞控制算法支持
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```bash
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cat /proc/sys/net/ipv4/tcp_available_congestion_control
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```
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> **注意**：若输出不包含`bbr`，则后续配置保持`cubic`。
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---
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## 2. BDP计算与参数确定
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### 2.1 计算公式
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`最大缓冲区(MB) ≈ 带宽(Mbps) × 0.125 × 最大RTT(秒)`
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即：`带宽(Mbps) × 0.125 × (RTT_ms / 1000)`
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### 2.2 参数参考
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| 场景 | 预估RTT | 推荐`max`值 |
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| :--- | :--- | :--- |
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| 本地网络 | ~30ms | 根据实测带宽计算 |
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| 代理/国际链路 | ~150-200ms | 根据实测带宽计算 |
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| **内存<1GB设备** | - | **固定16MB** |
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| 大内存服务器 | - | 可参考GCP建议最大64MB |
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### 2.3 配置示例（16MB）
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若计算后决定使用16MB上限：
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```bash
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cat > /etc/sysctl.d/90-tcp-tuning.conf <<'EOF'
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net.core.rmem_max = 16777216
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net.core.wmem_max = 16777216
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net.ipv4.tcp_rmem = 4096 131072 16777216
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net.ipv4.tcp_wmem = 4096 16384 16777216
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net.core.netdev_max_backlog = 8192
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net.ipv4.tcp_mtu_probing = 1
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net.ipv4.tcp_fastopen = 3
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net.ipv4.tcp_slow_start_after_idle = 0
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EOF
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```
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---
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## 3. 应用与验证
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### 3.1 加载配置
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```bash
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# 应用配置文件（BusyBox使用-p参数）
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sysctl -p /etc/sysctl.d/90-tcp-tuning.conf
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```
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### 3.2 验证生效
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```bash
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# 检查关键参数
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sysctl net.ipv4.tcp_rmem net.core.rmem_max
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```
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### 3.3 本地环回吞吐测试
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```bash
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# 启动临时服务端（运行1次后退出）
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iperf3 -s -1 &
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# 客户端连接本机测试（3秒）
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iperf3 -c 127.0.0.1 -t 3
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```
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> **目的**：验证内核TCP栈本身是否正常。
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---
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## 4. 重要说明
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- **开机自动加载**：OpenWrt系统下，`/etc/init.d/sysctl`会自动遍历`/etc/sysctl.d/*.conf`，无需额外设置。
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- **BBR支持**：若内核不支持BBR，不添加`net.ipv4.tcp_congestion_control=bbr`，保留默认cubic。
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- **故障排查**：外网测速慢时，请先排除：
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- 代理软件（openclash/mihomo）劫持流量。
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- 上游运营商或国际链路瓶颈。
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- **配置回滚**：如需恢复默认设置，只需：
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```bash
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rm /etc/sysctl.d/90-tcp-tuning.conf
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sysctl -p /etc/sysctl.d/90-tcp-tuning.conf # 或重启设备
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```
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---
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