CPU and state topology is cached for 30s.

server/services/collectors/cgroups.js

@@ -216,6 +216,7 @@ export class CgroupsCollector extends EventEmitter {
     /** @type {Array<{ id: string, title: string, path: string }>|null} */
     this._cgCache = null
     this._cgTs = 0
+    this._cgTick = 0
   }
 
   start() {
@@ -285,6 +286,9 @@ export class CgroupsCollector extends EventEmitter {
       }
     }
     const cgList = this._cgCache
+    const doMemDetail = this._cgTick % 5 === 0
+    const doPressure = this._cgTick % 3 === 0
+    this._cgTick++
 
     for (const cg of cgList) {
       const title = resolveContainerLabel(cg.title, this._names)
@@ -347,7 +351,10 @@ export class CgroupsCollector extends EventEmitter {
         },
       })
 
-      const memStat = profile('memStat:' + cg.id.slice(0,20), () => parseMemoryStat(cg.path))
+      let memStat = null
+      if (doMemDetail) {
+        memStat = profile('memStat:' + cg.id.slice(0,20), () => parseMemoryStat(cg.path))
+      }
       if (memStat) {
         batch.push({
           chart: memDetailDef.id,
@@ -374,17 +381,19 @@ export class CgroupsCollector extends EventEmitter {
         values: { throttled: throttlePct },
       })
 
-      for (const kind of ['cpu', 'memory', 'io']) {
-        const some10 = parsePressureSome10(cg.path, kind)
-        if (some10 == null) continue
-        const pressureDef = makeCgroupPressureChart(cg.id, title, kind)
-        registerChart(pressureDef)
-        batch.push({
-          chart: pressureDef.id,
-          context: 'cgroup.pressure',
-          ts,
-          values: { some10 },
-        })
+      if (doPressure) {
+        for (const kind of ['cpu', 'memory', 'io']) {
+          const some10 = parsePressureSome10(cg.path, kind)
+          if (some10 == null) continue
+          const pressureDef = makeCgroupPressureChart(cg.id, title, kind)
+          registerChart(pressureDef)
+          batch.push({
+            chart: pressureDef.id,
+            context: 'cgroup.pressure',
+            ts,
+            values: { some10 },
+          })
+        }
       }
 
       this.prev.set(cg.id, {

server/services/collectors/host-more.js

@@ -208,32 +208,53 @@ export function collectNumaNodes(batch, ts) {
  */
 export function collectCpuidle(batch, ts, dtSec, state) {
   if (os.platform() !== 'linux') return
-  const cpuRoot = '/sys/devices/system/cpu'
-  let dirs
-  try {
-    dirs = fs.readdirSync(cpuRoot).filter((d) => /^cpu\d+$/.test(d))
-  } catch {
-    return
+  // cache cpuidle state paths for 30s — topology doesn't change at runtime
+  let cpuidlePaths = state._cpuidlePaths
+  const now = Date.now()
+  if (!cpuidlePaths || now - cpuidlePaths.ts > 30000) {
+    const cpuRoot = '/sys/devices/system/cpu'
+    let dirs
+    try {
+      dirs = fs.readdirSync(cpuRoot).filter((d) => /^cpu\d+$/.test(d))
+    } catch {
+      return
+    }
+    /** @type {Record<string, Array<{ nameFile: string, timeFile: string }>>} */
+    const entries = {}
+    for (const d of dirs) {
+      const coreId = d.slice(3)
+      const idleDir = path.join(cpuRoot, d, 'cpuidle')
+      let states
+      try {
+        states = fs.readdirSync(idleDir).filter((s) => /^state\d+$/.test(s))
+      } catch {
+        continue
+      }
+      const files = []
+      for (const s of states) {
+        files.push({
+          nameFile: path.join(idleDir, s, 'name'),
+          timeFile: path.join(idleDir, s, 'time'),
+        })
+      }
+      if (files.length) entries[coreId] = files
+    }
+    cpuidlePaths = { ts: now, entries, cpuDirs: dirs }
+    state._cpuidlePaths = cpuidlePaths
   }
+  const { entries } = cpuidlePaths
   const prevAll = state.lastIdle || {}
   /** @type {Record<string, Record<string, number>>} */
   const nextAll = {}
 
-  for (const d of dirs) {
-    const coreId = d.slice(3)
-    const idleDir = path.join(cpuRoot, d, 'cpuidle')
-    let states
-    try {
-      states = fs.readdirSync(idleDir).filter((s) => /^state\d+$/.test(s))
-    } catch {
-      continue
-    }
+  for (const coreId of Object.keys(entries)) {
+    const files = entries[coreId]
     /** @type {Record<string, number>} */
     const times = {}
-    for (const s of states) {
-      const name = (readFile(path.join(idleDir, s, 'name')) || s).trim().toLowerCase().replace(/\s+/g, '_')
-      const t = Number(readFile(path.join(idleDir, s, 'time')) || 0) // µs
-      times[name || s] = t
+    for (const { nameFile, timeFile } of files) {
+      const name = (readFile(nameFile) || '').trim().toLowerCase().replace(/\s+/g, '_')
+      const t = Number(readFile(timeFile) || 0) // µs
+      times[name || 'state'] = t
     }
     nextAll[coreId] = times
     const prev = prevAll[coreId]