feat: capture system stats in benchmark

app/benchmark/systemStats.ts

@@ -0,0 +1,136 @@
+import { readFile } from 'node:fs/promises';
+import { cpus, totalmem } from 'node:os';
+
+export type CpuSnapshot = {
+  idle: number;
+  total: number;
+  steal: number;
+};
+
+export type SystemSample = {
+  timestamp: number;
+  cpuUsagePercent: number;
+  cpuStealPercent: number;
+  load1: number;
+  load5: number;
+  load15: number;
+  freeMemory: number;
+  totalMemory: number;
+};
+
+export async function readCpuSnapshot(): Promise<CpuSnapshot> {
+  const stat = await readFile('/proc/stat', 'utf8');
+  const line = stat.split('\n')[0];
+
+  const parts = line
+    .trim()
+    .split(/\s+/)
+    .slice(1)
+    .map(v => Number(v));
+
+  const [
+    user,
+    nice,
+    system,
+    idle,
+    iowait,
+    irq,
+    softirq,
+    steal
+  ] = parts;
+
+  return {
+    idle: idle + iowait,
+    total: parts.reduce((a, b) => a + b, 0),
+    steal: steal ?? 0
+  };
+}
+
+export async function measureCpuUsage(
+  previous: CpuSnapshot
+): Promise<{
+  snapshot: CpuSnapshot;
+  usagePercent: number;
+  stealPercent: number;
+}> {
+  const current = await readCpuSnapshot();
+
+  const idle = current.idle - previous.idle;
+  const total = current.total - previous.total;
+  const steal = current.steal - previous.steal;
+
+  return {
+    snapshot: current,
+    usagePercent: total === 0 ? 0 : 100 * (1 - idle / total),
+    stealPercent: total === 0 ? 0 : 100 * (steal / total)
+  };
+}
+
+export async function readCgroupCpuStat() {
+  const possiblePaths = [
+    '/sys/fs/cgroup/cpu.stat',
+    '/sys/fs/cgroup/cpu/cpu.stat'
+  ];
+
+  for (const path of possiblePaths) {
+    try {
+      const txt = await readFile(path, 'utf8');
+
+      return Object.fromEntries(
+        txt
+          .trim()
+          .split('\n')
+          .map(line => {
+            const [k, v] = line.trim().split(/\s+/);
+            return [k, Number(v)];
+          })
+      );
+    } catch {
+      // continue
+    }
+  }
+
+  return null;
+}
+
+export async function readProcMemInfo() {
+  try {
+    const txt = await readFile('/proc/meminfo', 'utf8');
+
+    const result: Record<string, number> = {};
+
+    for (const line of txt.split('\n')) {
+      const match = line.match(/^(\w+):\s+(\d+)/);
+
+      if (!match) continue;
+
+      result[match[1]] = Number(match[2]);
+    }
+
+    return result;
+  } catch {
+    return null;
+  }
+}
+
+export function getMachineInfo() {
+  const cpuInfo = cpus();
+
+  return {
+    platform: process.platform,
+    arch: process.arch,
+    nodeVersion: process.version,
+
+    cpuModel: cpuInfo[0]?.model ?? 'unknown',
+    cpuCount: cpuInfo.length,
+
+    totalMemory: totalmem(),
+
+    ci: {
+      githubActions: process.env.GITHUB_ACTIONS ?? false,
+      runnerName: process.env.RUNNER_NAME ?? null,
+      runnerOs: process.env.RUNNER_OS ?? null,
+      runnerArch: process.env.RUNNER_ARCH ?? null
+    }
+  };
+}