..標題：Linux TCP Sysctl 調優參考
.. slug: linux-tcp-sysctl-參考
.. 日期: 2026-03-27 12:00:00 世界標準時間
.. 標籤：linux、tcp、sysctl、效能、核心、計算器、工具
..類別：計算器
..連結：
.. 描述：互動式 Linux net.ipv4.tcp_* 和 net.core.* 參數指南，其中包含批次傳輸、延遲敏感的 RPC、高連接 Web 伺服器和長寬管 WAN 的工作負載預設。
..類型：文字
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<h2>Linux TCP Sysctl 調優參考</h2>
<p>互動的<code style="color:rgba(255,255,255,0.9)">net.ipv4.tcp_*</code>和<code style="color:rgba(255,255,255,0.9)">net.core.*</code>參數指南，其中包含批次傳輸、延遲敏感的 RPC、高連接 Web 伺服器和長寬管 WAN 的工作負載預設。</p>
<div class="input-grid">
<div class="input-group">
<label>搜尋/過濾</label>
<input id="searchInput" oninput="filterParams(this.value)" placeholder="Search parameters..." type="text"/>
</div>
<div class="input-group">
<label>工作負載預設</label>
<div class="preset-row" id="presetRow"></div>
</div>
</div>
</div>
<div class="result-section">
<div class="section-header">TCP 系統參數</div>
<div class="section-content" id="paramList">
</div>
<div style="padding: 20px; background: #fafafa; border-top: 1px solid #e0e0e0;">
<button class="copy-all-btn" onclick="copyAll()">將所有顯示的參數複製為 sysctl 命令</button>
</div>
</div>
</div>
<script>
const PARAMS = [
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        name: 'net.ipv4.tcp_rmem',
        desc: 'TCP receive buffer sizes: min, default, max (bytes). Kernel auto-tunes between min and max.',
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        doc: 'https://www.kernel.org/doc/html/latest/networking/ip-sysctl.html',
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        range: 'min 4096; max up to ~1GB',
        tags: ['buffer', 'send', 'window'],
        doc: 'https://www.kernel.org/doc/html/latest/networking/ip-sysctl.html',
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    {
        name: 'net.core.rmem_max',
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        name: 'net.core.wmem_max',
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        doc: 'https://www.kernel.org/doc/html/latest/networking/ip-sysctl.html',
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    {
        name: 'net.ipv4.tcp_congestion_control',
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            bulk: 'bbr',
            rpc: 'cubic',
            web: 'bbr',
            wan: 'bbr',
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        range: 'cubic, bbr, reno, htcp (check: sysctl net.ipv4.tcp_available_congestion_control)',
        tags: ['congestion', 'bbr', 'cubic'],
        doc: 'https://www.kernel.org/doc/html/latest/networking/ip-sysctl.html',
    },
    {
        name: 'net.ipv4.tcp_window_scaling',
        desc: 'Enable TCP window scaling (RFC 1323). Required for windows > 65535 bytes.',
        default: '1',
        presets: { bulk: '1', rpc: '1', web: '1', wan: '1' },
        range: '0 (disable) or 1 (enable)',
        tags: ['window', 'rfc1323'],
        doc: 'https://www.kernel.org/doc/html/latest/networking/ip-sysctl.html',
    },
    {
        name: 'net.ipv4.tcp_timestamps',
        desc: 'RFC 1323 timestamps — used for PAWS (protection against wrapped sequence numbers) and RTT measurement.',
        default: '1',
        presets: { bulk: '1', rpc: '1', web: '1', wan: '1' },
        range: '0 (disable), 1 (enable), 2 (enable without ECR)',
        tags: ['rfc1323', 'paws', 'rtt'],
        doc: 'https://www.kernel.org/doc/html/latest/networking/ip-sysctl.html',
    },
    {
        name: 'net.ipv4.tcp_sack',
        desc: 'Selective Acknowledgements (RFC 2018). Allows receiver to inform sender of non-contiguous received segments, improving recovery from multiple losses.',
        default: '1',
        presets: { bulk: '1', rpc: '1', web: '1', wan: '1' },
        range: '0 or 1',
        tags: ['sack', 'loss', 'recovery'],
        doc: 'https://www.kernel.org/doc/html/latest/networking/ip-sysctl.html',
    },
    {
        name: 'net.ipv4.tcp_max_syn_backlog',
        desc: 'Maximum number of SYN packets queued per listening socket before dropping. Increase for high connection-rate servers.',
        default: '1024',
        presets: {
            bulk: '1024',
            rpc: '4096',
            web: '65536',
            wan: '1024',
        },
        range: '128 – 65536 (limited by system memory)',
        tags: ['syn', 'connection', 'backlog'],
        doc: 'https://www.kernel.org/doc/html/latest/networking/ip-sysctl.html',
    },
    {
        name: 'net.core.somaxconn',
        desc: 'Maximum socket listen backlog (accept queue depth). Application must also set listen() backlog >= this value.',
        default: '4096',
        presets: {
            bulk: '4096',
            rpc: '8192',
            web: '65535',
            wan: '4096',
        },
        range: '128 – 65535',
        tags: ['connection', 'backlog', 'accept', 'core'],
        doc: 'https://www.kernel.org/doc/html/latest/networking/ip-sysctl.html',
    },
    {
        name: 'net.ipv4.tcp_tw_reuse',
        desc: 'Allow reuse of TIME_WAIT sockets for new connections when safe (requires timestamps). Reduces port exhaustion under heavy connection churn.',
        default: '2',
        presets: {
            bulk: '2',
            rpc: '1',
            web: '1',
            wan: '2',
        },
        range: '0 (disable), 1 (enable for loopback), 2 (enable for all)',
        tags: ['time_wait', 'port', 'reuse'],
        doc: 'https://www.kernel.org/doc/html/latest/networking/ip-sysctl.html',
    },
    {
        name: 'net.ipv4.tcp_fin_timeout',
        desc: 'Time (seconds) a socket stays in FIN_WAIT_2 state before being forcibly closed. Reduce to reclaim ports faster under high connection rates.',
        default: '60',
        presets: {
            bulk: '60',
            rpc: '15',
            web: '15',
            wan: '60',
        },
        range: '5 – 120 seconds',
        tags: ['fin', 'timeout', 'connection'],
        doc: 'https://www.kernel.org/doc/html/latest/networking/ip-sysctl.html',
    },
];

const PRESETS = {
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    rpc: { label: 'Latency-Sensitive RPC', desc: 'Low-latency datacenter RPCs (Redis, gRPC, etc.)' },
    web: { label: 'High-Connection Web Server', desc: 'High connection rate, many short-lived connections' },
    wan: { label: 'Long-Fat-Pipe WAN', desc: 'High bandwidth × high RTT (satellite, cross-continental)' },
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    list.innerHTML = filtered.map((p, idx) => {
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        const tags = p.tags.map(t => `<span class="param-tag">${t}</span>`).join('');
        const changed = currentPreset !== 'default' && val !== p.default;
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                    <span><strong>Default:</strong> ${p.default}</span>
                    <span><strong>Range:</strong> ${p.range}</span>
                </div>
                <div style="margin-top:8px">${tags}</div>
                <div class="copy-block">${cmd} <button class="copy-btn" onclick="copyCmd('${cmd}')">Copy</button></div>
            </div>
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function copyCmd(cmd) {
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}

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init();
</script>