.. タイトル: NIC リング バッファおよび IRQ アフィニティ カリキュレータ
.. スラグ: nic-ring-buffer-calculator
.. 日付: 2026-03-27 12:00:00 UTC
.. タグ: Linux、NIC、IRQ、RSS、パフォーマンス、カーネル、電卓、ツール
.. カテゴリ: 電卓
..リンク:
.. 説明: インターフェイス速度、CPU 数、トラフィック プロファイルに基づいて、推奨される ethtool リング バッファ サイズ、RSS キュー数、および CPU アフィニティ ピンニング戦略を計算します。
.. タイプ: テキスト
<style>
.calc-container { max-width: 900px; margin: 20px auto; padding: 20px; }
.calc-header { margin-bottom: 30px; padding: 25px; background: linear-gradient(135deg, #667eea 0%, #764ba2 100%); border-radius: 12px; box-shadow: 0 4px 6px rgba(0,0,0,0.1); color: white; }
.calc-header h2 { margin-top: 0; color: white; font-size: 28px; margin-bottom: 10px; }
.calc-header p  { margin: 10px 0; opacity: 0.95; font-size: 15px; }
.input-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 15px; margin-top: 20px; }
.input-group { display: flex; flex-direction: column; }
.input-group label { margin-bottom: 8px; font-weight: 600; color: rgba(255,255,255,0.95); font-size: 14px; }
.input-group input, .input-group select { padding: 14px; font-size: 14px; border: 2px solid rgba(255,255,255,0.3); border-radius: 6px; background: rgba(255,255,255,0.95); transition: all 0.3s ease; box-sizing: border-box; }
.input-group input:focus, .input-group select:focus { outline: none; border-color: #4CAF50; background: white; box-shadow: 0 0 0 3px rgba(76,175,80,0.1); }
.button-container { margin-top: 20px; display: flex; justify-content: center; gap: 10px; flex-wrap: wrap; }
.calc-button { padding: 14px 35px; font-size: 16px; background: #4CAF50; color: white; border: none; border-radius: 6px; cursor: pointer; font-weight: bold; transition: all 0.3s ease; box-shadow: 0 2px 4px rgba(0,0,0,0.2); }
.calc-button:hover { background: #45a049; transform: translateY(-1px); box-shadow: 0 4px 8px rgba(0,0,0,0.3); }
.calc-button:active { background: #3d8b40; transform: translateY(0); }
.help-text { margin-top: 15px; font-size: 14px; color: rgba(255,255,255,0.9); background: rgba(0,0,0,0.1); padding: 10px 15px; border-radius: 4px; }
.result-section { background: white; border: 1px solid #e0e0e0; border-radius: 8px; margin-top: 20px; overflow: hidden; box-shadow: 0 2px 4px rgba(0,0,0,0.05); transition: all 0.3s ease; }
.result-section:hover { box-shadow: 0 4px 8px rgba(0,0,0,0.1); }
.section-header { background: linear-gradient(135deg, #4CAF50 0%, #45a049 100%); color: white; padding: 15px 20px; font-size: 18px; font-weight: bold; }
.section-content { padding: 20px; background: #fafafa; }
.result-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 15px; }
.data-row { display: flex; flex-direction: column; padding: 15px; background: white; border-radius: 6px; border-left: 4px solid #4CAF50; box-shadow: 0 1px 3px rgba(0,0,0,0.05); }
.data-label { font-weight: bold; color: #555; font-size: 13px; margin-bottom: 8px; text-transform: uppercase; letter-spacing: 0.5px; }
.data-value { color: #4CAF50; font-family: 'Courier New', monospace; font-size: 20px; font-weight: bold; }
.data-value.small { font-size: 14px; }
.info-box { margin-top: 15px; padding: 15px; background: #e3f2fd; color: #1565c0; border-radius: 8px; border-left: 4px solid #2196F3; font-size: 14px; line-height: 1.6; }
table { width: 100%; border-collapse: collapse; }
th { background: linear-gradient(135deg, #4CAF50 0%, #45a049 100%); color: white; padding: 10px; text-align: left; }
td { padding: 8px 10px; border-bottom: 1px solid #eee; font-size: 13px; }
tr:hover td { background: #f8fff8; }
@media (max-width: 768px) { .input-grid, .result-grid { grid-template-columns: 1fr; } .calc-header h2 { font-size: 22px; } .calc-container { padding: 10px; } }
/* Page-specific */
.cmd-block { background: #1e1e2e; color: #cdd6f4; padding: 10px 14px; border-radius: 6px; font-family: 'Courier New', monospace; font-size: 12px; overflow-x: auto; white-space: pre; margin: 8px 0; }
.metric-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 15px; }
.metric-card { display: flex; flex-direction: column; padding: 15px; background: white; border-radius: 6px; border-left: 4px solid #4CAF50; box-shadow: 0 1px 3px rgba(0,0,0,0.05); }
.metric-label { font-weight: bold; color: #555; font-size: 13px; margin-bottom: 6px; text-transform: uppercase; }
.metric-value { color: #4CAF50; font-family: 'Courier New', monospace; font-size: 18px; font-weight: bold; }
.result-highlight { color: #4CAF50; font-weight: bold; font-size: 1.2em; }
</style>
<div class="calc-container">
<div class="calc-header">
<h2>NIC リング バッファおよび IRQ アフィニティ カリキュレータ</h2>
<p>計算する<code style="color:rgba(255,255,255,0.9);background:rgba(0,0,0,0.2);padding:2px 6px;border-radius:3px">ethtool -G</code>リング バッファ サイズ、RSS キュー数、CPU アフィニティ/irqbalance ピンニング戦略。</p>
<div class="input-grid">
<div class="input-group">
<label>インターフェース速度</label>
<select id="linkSpeed">
<option value="1">1Gbps</option>
<option selected="" value="10">10Gbps</option>
<option value="25">25Gbps</option>
<option value="40">40Gbps</option>
<option value="100">100Gbps</option>
</select>
</div>
<div class="input-group">
<label>利用可能なCPUコア</label>
<input id="cpuCount" max="256" min="1" type="number" value="8"/>
</div>
<div class="input-group">
<label>トラフィックプロファイル</label>
<select id="trafficProfile">
<option value="bulk">バルク/ストリーミング (大きなフレーム)</option>
<option selected="" value="rpc">混合 / RPC (可変フレーム サイズ)</option>
<option value="pps">高い PPS (小さなフレーム)</option>
</select>
</div>
<div class="input-group">
<label>割り込み合体ターゲット (μs)</label>
<input id="coalesceUs" max="1000" min="1" type="number" value="50"/>
</div>
<div class="input-group">
<label>インターフェース名</label>
<input id="ifName" placeholder="eth0" type="text" value="eth0"/>
</div>
</div>
<div class="button-container">
<button class="calc-button" onclick="calcNic()">計算する</button>
</div>
</div>
<div id="nicResult" style="display:none"></div>
<div class="result-section">
<div class="section-header">リングバッファとドロップ率のトレードオフ</div>
<div class="section-content">
<table>
<tr><th>リングサイズ</th><th>レイテンシの影響</th><th>ドロップリスク</th><th>使用事例</th></tr>
<tr><td>256</td><td>非常に低い</td><td>高(バーストドロップ)</td><td>リアルタイム、低遅延の優先順位</td></tr>
<tr><td>512</td><td>低い</td><td>中くらい</td><td>遅延に敏感な RPC</td></tr>
<tr><td>1024</td><td>中くらい</td><td>低い</td><td>汎用</td></tr>
<tr><td>2048</td><td>中～高</td><td>非常に低い</td><td>バルク転送、10Gbps+</td></tr>
<tr><td>4096</td><td>高 (遅延が追加される)</td><td>最小限</td><td>100Gbps、持続的な PPS</td></tr>
</table>
</div>
</div>
</div>
<script>
function calcNic() {
    const speedGbps = parseInt(document.getElementById('linkSpeed').value);
    const cpus = parseInt(document.getElementById('cpuCount').value);
    const profile = document.getElementById('trafficProfile').value;
    const coalesceUs = parseInt(document.getElementById('coalesceUs').value);
    const iface = document.getElementById('ifName').value.trim() || 'eth0';
    const div = document.getElementById('nicResult');
    div.style.display = 'block';

    if (isNaN(cpus) || cpus < 1 || isNaN(coalesceUs) || coalesceUs < 1) {
        div.innerHTML = '<div class="result-section"><div class="section-header">Results</div><div class="section-content"><strong style="color:red">Invalid input.</strong></div></div>';
        return;
    }

    // Ring buffer sizing: ceil(link_speed_bps * coalesce_delay_s / (8 * frame_size))
    // Frame size heuristic by profile
    const frameSizes = { bulk: 9000, rpc: 1500, pps: 64 };
    const frameSize = frameSizes[profile];
    const speedBps = speedGbps * 1e9;
    const coalesceS = coalesceUs / 1e6;
    const rawRing = Math.ceil((speedBps * coalesceS) / (8 * frameSize));
    // Round up to nearest power of 2 (common NIC constraint)
    let ringSize = 1;
    while (ringSize < rawRing) ringSize *= 2;
    ringSize = Math.min(ringSize, 4096); // max typical ring size

    // RSS queues: min(cpus, speed-based cap, 64)
    const speedQueues = speedGbps <= 1 ? 4 : speedGbps <= 10 ? 8 : speedGbps <= 25 ? 16 : 32;
    const rssQueues = Math.min(cpus, speedQueues, 64);

    // CPU affinity: prefer first N CPUs, skip CPU 0 if NUMA/irqbalance concern
    const affinityCpus = rssQueues <= 4 ? `1-${rssQueues}` : `0-${rssQueues - 1}`;

    div.innerHTML = `<div class="result-section">
        <div class="section-header">Recommended Settings</div>
        <div class="section-content">
            <div class="metric-grid">
                <div class="metric-card"><div class="metric-value">${ringSize}</div><div class="metric-label">Ring buffer size (RX &amp; TX)</div></div>
                <div class="metric-card"><div class="metric-value">${rssQueues}</div><div class="metric-label">RSS queues</div></div>
                <div class="metric-card"><div class="metric-value">${coalesceUs} μs</div><div class="metric-label">Interrupt coalescing</div></div>
                <div class="metric-card"><div class="metric-value">${speedGbps} Gbps</div><div class="metric-label">Link speed</div></div>
            </div>
            <div class="info-box">
                <strong>Calculation:</strong> ceil(${speedGbps}Gbps &times; ${coalesceUs}μs / (8 &times; ${frameSize}B)) = ${rawRing} &rarr; rounded up to ${ringSize} (power of 2)
            </div>
            <div class="cmd-block"># Set ring buffer (${iface})
ethtool -G ${iface} rx ${ringSize} tx ${ringSize}

# Set RSS queue count
ethtool -L ${iface} combined ${rssQueues}

# Set interrupt coalescing
ethtool -C ${iface} rx-usecs ${coalesceUs} tx-usecs ${coalesceUs}

# Pin IRQs to CPUs ${affinityCpus} (run after ethtool -L)
# Find IRQ numbers: grep ${iface} /proc/interrupts | awk '{print $1}' | tr -d ':'
# Then: echo ${affinityCpus} > /proc/irq/&lt;N&gt;/smp_affinity_list

# Or use irqbalance with policy hint:
IRQBALANCE_ARGS="--policyscript=/etc/irqbalance/policy.sh" systemctl restart irqbalance</div>
            <button class="calc-button" style="margin-top:10px;padding:10px 24px;font-size:14px" onclick="copyBlock()">Copy Commands</button>
        </div>
    </div>`;

    window._lastCmds = `# Set ring buffer (${iface})\nethtool -G ${iface} rx ${ringSize} tx ${ringSize}\n\n# Set RSS queue count\nethtool -L ${iface} combined ${rssQueues}\n\n# Set interrupt coalescing\nethtool -C ${iface} rx-usecs ${coalesceUs} tx-usecs ${coalesceUs}`;
}

function copyBlock() {
    if (!window._lastCmds) return;
    navigator.clipboard.writeText(window._lastCmds).catch(() => {
        const ta = document.createElement('textarea');
        ta.value = window._lastCmds; document.body.appendChild(ta); ta.select(); document.execCommand('copy'); ta.remove();
    });
}
</script>