Fix cpu percentage formula

soyuka · Jun 3, 2018 · 88972d8 · 88972d8
1 parent 174fe65
commit 88972d8
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Showing 5 changed files with 36 additions and 27 deletions.
diff --git a/README.md b/README.md
@@ -25,7 +25,7 @@ setInterval(function () {
   pidusage(process.pid, function (err, stats) {
     console.log(stats)
     // => {
-    //   cpu: 10.0,            // percentage (it may happen to be greater than 100%)
+    //   cpu: 10.0,            // percentage (0-100%)
     //   memory: 357306368,    // bytes
     //   ppid: 312,            // PPID
     //   pid: 727,             // PID
@@ -41,7 +41,7 @@ pidusage([727, 1234], function (err, stats) {
   console.log(stats)
   // => {
   //   727: {
-  //     cpu: 10.0,            // percentage
+  //     cpu: 10.0,            // percentage (0-100%)
   //     memory: 357306368,    // bytes
   //     ppid: 312,            // PPID
   //     pid: 727,             // PID
@@ -50,7 +50,7 @@ pidusage([727, 1234], function (err, stats) {
   //     timestamp: 864000000  // ms since epoch
   //   },
   //   1234: {
-  //     cpu: 0.1,             // percentage
+  //     cpu: 0.1,             // percentage (0-100%)
   //     memory: 3846144,      // bytes
   //     ppid: 727,            // PPID
   //     pid: 1234,            // PID
@@ -65,7 +65,7 @@ pidusage([727, 1234], function (err, stats) {
 const stats = await pidusage(process.pid)
 console.log(stats)
 // => {
-//   cpu: 10.0,            // percentage (it may happen to be greater than 100%)
+//   cpu: 10.0,            // percentage (0-100%)
 //   memory: 357306368,    // bytes
 //   ppid: 312,            // PPID
 //   pid: 727,             // PID
@@ -135,4 +135,3 @@ This project is licensed under the MIT License - see the [LICENSE][license] file
 
 [node:cpuUsage]: https://nodejs.org/api/process.html#process_process_cpuusage_previousvalue
 [node:memUsage]: https://nodejs.org/api/process.html#process_process_memoryusage
-
diff --git a/lib/procfile.js b/lib/procfile.js
@@ -3,7 +3,7 @@ var path = require('path')
 var updateCpu = require('./helpers/cpu')
 var parallel = require('./helpers/parallel')
 var history = require('./history')
-var cpu = null
+var cpuInfo = null
 
 function readProcFile (pid, options, done) {
   var hst = history.get(pid, options.maxage)
@@ -18,7 +18,7 @@ function readProcFile (pid, options, done) {
       return done(err, null)
     }
     var date = Date.now()
-    
+
     // https://github.com/arunoda/node-usage/commit/a6ca74ecb8dd452c3c00ed2bde93294d7bb75aa8
     // preventing process space in name by removing values before last ) (pid (name) ...)
     var index = infos.lastIndexOf(')')
@@ -32,29 +32,28 @@ function readProcFile (pid, options, done) {
       stime: parseFloat(infos[12]),
       cutime: parseFloat(infos[13]),
       cstime: parseFloat(infos[14]),
-      start: parseFloat(infos[19]) / cpu.clockTick,
+      start: parseFloat(infos[19]) / cpuInfo.clockTick,
       rss: parseFloat(infos[21]),
-      uptime: cpu.uptime
+      uptime: cpuInfo.uptime
     }
 
-    var memory = stat.rss * cpu.pageSize
+    var memory = stat.rss * cpuInfo.pageSize
 
     // https://stackoverflow.com/a/16736599/3921589
     var childrens = options.childrens ? stat.cutime + stat.cstime : 0
     // process usage since last call in seconds
-    var total = (stat.stime - (hst.stime || 0) + stat.utime - (hst.utime || 0) + childrens) / cpu.clockTick
+    var total = (stat.stime - (hst.stime || 0) + stat.utime - (hst.utime || 0) + childrens) / cpuInfo.clockTick
     // time elapsed between calls in seconds
     var seconds = Math.abs(hst.uptime !== undefined ? stat.uptime - hst.uptime : stat.start - stat.uptime)
-    if (seconds === 0) seconds = 1 // we sure can't divide through 0
+    var cpu = seconds > 0 ? (total / seconds) * 100 : 0
 
     history.set(stat, options.maxage)
 
-    var cpuPercent = Math.min(Math.round((total / seconds) * 100000) / 1000, 100.0)
 
     return done(null, {
-      cpu: cpuPercent,
+      cpu: Math.min(cpu, 100.0),
       memory: memory,
-      ctime: (stat.utime + stat.stime) / cpu.clockTick,
+      ctime: (stat.utime + stat.stime) / cpuInfo.clockTick,
       elapsed: date - (stat.start * 1000),
       timestamp: stat.start * 1000, // start date
       pid: pid,
@@ -64,10 +63,10 @@ function readProcFile (pid, options, done) {
 }
 
 function procfile (pid, options, done) {
-  updateCpu(cpu, function (err, result) {
+  updateCpu(cpuInfo, function (err, result) {
     if (err) return done(err)
 
-    cpu = result
+    cpuInfo = result
     var fns = {}
 
     pid.forEach(function (id, i) {

diff --git a/lib/ps.js b/lib/ps.js
@@ -4,6 +4,7 @@ var os = require('os')
 var bin = require('./bin')
 
 var PLATFORM = os.platform()
+var cpus = os.cpus().length
 
 function parseTime (timestr, fraction) {
   var time = 0
@@ -56,6 +57,7 @@ function ps (pids, options, done) {
     // ELAPSED: format is [[dd-]hh:]mm:ss
     // RSS: is counted as blocks of 1024 bytes
     // TIME: format is [[dd-]hh:]mm:ss
+    // %CPU: goes from 0 to vcore * 100
     //
     // Refs: http://www.manpages.info/linux/ps.1.html
     // NB: The columns are returned in the order given inside the -o option
@@ -70,6 +72,7 @@ function ps (pids, options, done) {
     // ELAPSED: format is [[dd-]hh:]mm:ss
     // RSS: is counted as blocks of 1024 bytes
     // TIME: format is [[dd-]hh:]ss:mm.pp (pp is the percentage of a minute)
+    // %CPU: goes from 0 to vcore * 100
     //
     // Refs: https://ss64.com/osx/ps.html
     // NB: The columns are returned in the order given inside the -o option
@@ -92,13 +95,13 @@ function ps (pids, options, done) {
 
       var pid = parseInt(line[1], 10)
       var ppid = parseInt(line[2], 10)
-      var cpu = parseFloat(line[3].replace(',', '.'), 10)
+      var cpu = parseFloat(line[3].replace(',', '.'), 10) / cpus
       var memory = parseInt(line[4], 10) * 1024
       var etime = parseTime(line[0])
       var ctime = parseTime(line[5], true)
 
       statistics[pid] = {
-        cpu: Math.min(Math.round(cpu * 1000) / 1000, 100.0),
+        cpu: Math.min(cpu, 100.0),
         memory: memory,
         ppid: ppid,
         pid: pid,

diff --git a/lib/wmic.js b/lib/wmic.js
@@ -99,15 +99,15 @@ function wmic (pids, options, done) {
       }
 
       // process usage since last call
-      var total = (kerneltime + usertime - hst.ctime)
-      // time elapsed between calls
+      var total = (kerneltime + usertime - hst.ctime) / 1000
+      // time elapsed between calls in seconds
       var seconds = uptime - hst.uptime
-      var cpu = seconds > 0 ? (total / (seconds * 1000)) * 100 : 0
+      var cpu = seconds > 0 ? (total / seconds) * 100 : 0
 
       history.set(pid, {ctime: usertime + kerneltime, uptime: uptime}, options.maxage)
 
       statistics[pid] = {
-        cpu: Math.min(Math.round(cpu * 1000) / 1000, 100.0),
+        cpu: Math.min(cpu, 100.0),
         memory: memory,
         ppid: ppid,
         pid: pid,

diff --git a/test/ps.js b/test/ps.js
@@ -38,8 +38,12 @@ test('should parse ps output on Darwin', async t => {
     spawn: () => mocks.spawn(stdout, '', null, 0, null)
   })
   mockery.registerMock('os', {
-    EOL: os.EOL, platform: () => 'darwin', type: () => 'type', release: () => 'release'}
-  )
+    EOL: os.EOL,
+    platform: () => 'darwin',
+    type: () => 'type',
+    release: () => 'release',
+    cpus: () => [os.cpus()[0]]
+  })
 
   const ps = require('../lib/ps')
 
@@ -99,8 +103,12 @@ test('should parse ps output on *nix', async t => {
     spawn: () => mocks.spawn(stdout, '', null, 0, null)
   })
   mockery.registerMock('os', {
-    EOL: os.EOL, platform: () => 'linux', type: () => 'type', release: () => 'release'}
-  )
+    EOL: os.EOL,
+    platform: () => 'linux',
+    type: () => 'type',
+    release: () => 'release',
+    cpus: () => [os.cpus()[0]]
+  })
 
   const ps = require('../lib/ps')