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,
@@ -374,6 +381,7 @@ export class CgroupsCollector extends EventEmitter {
         values: { throttled: throttlePct },
       })
 
+      if (doPressure) {
         for (const kind of ['cpu', 'memory', 'io']) {
           const some10 = parsePressureSome10(cg.path, kind)
           if (some10 == null) continue
@@ -386,6 +394,7 @@ export class CgroupsCollector extends EventEmitter {
             values: { some10 },
           })
         }
+      }
 
       this.prev.set(cg.id, {
         usage: usageUsec,

server/services/collectors/host-more.js

@@ -208,6 +208,10 @@ export function collectNumaNodes(batch, ts) {
  */
 export function collectCpuidle(batch, ts, dtSec, state) {
   if (os.platform() !== 'linux') 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 {
@@ -215,10 +219,8 @@ export function collectCpuidle(batch, ts, dtSec, state) {
     } catch {
       return
     }
-  const prevAll = state.lastIdle || {}
-  /** @type {Record<string, Record<string, number>>} */
-  const nextAll = {}
-
+    /** @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')
@@ -228,12 +230,31 @@ export function collectCpuidle(batch, ts, dtSec, state) {
       } 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 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]