Convert the output of os.cpus() in Node.js to percentage

Is there a way to convert the os.cpus() info to percentage? Just like the output of iostat (on the CPU section).

My code:

var os = require('os');
console.log(os.cpus());

The output:

[ { model: 'MacBookAir4,2',
    speed: 1800,
    times: 
     { user: 5264280,
       nice: 0,
       sys: 4001110,
       idle: 58703910,
       irq: 0 } },
  { model: 'MacBookAir4,2',
    speed: 1800,
    times: 
     { user: 2215030,
       nice: 0,
       sys: 1072600,
       idle: 64657440,
       irq: 0 } },
  { model: 'MacBookAir4,2',
    speed: 1800,
    times: 
     { user: 5973360,
       nice: 0,
       sys: 3197990,
       idle: 58773760,
       irq: 0 } },
  { model: 'MacBookAir4,2',
    speed: 1800,
    times: 
     { user: 2187650,
       nice: 0,
       sys: 1042550,
       idle: 64714820,
       irq: 0 } } ]

I would like to have the "times" metric converted to percentage, just like is show on the iostat command:

  cpu
us sy id
6  3 91

I understand that the values in the nodejs function are in CPU ticks, but I have no idea what formula should I use to convert them to percentage :)

Thanks.

Linus Gustav Larsson Thiel

According to the docs, times is

an object containing the number of CPU ticks spent in: user, nice, sys, idle, and irq

So you should just be able to sum the times and calculate the percentage, like below:

var cpus = os.cpus();

for(var i = 0, len = cpus.length; i < len; i++) {
    console.log("CPU %s:", i);
    var cpu = cpus[i], total = 0;

    for(var type in cpu.times) {
        total += cpu.times[type];
    }

    for(type in cpu.times) {
        console.log("\t", type, Math.round(100 * cpu.times[type] / total));
    }
}

EDIT: As Tom Frost says in the comments, this is the average usage since system boot. This is consistent with the question, since the same is true of iostat. However, iostat has the option of doing regular updates, showing the average usage since the last update. Tom's method would work well for implementing that.

This module, that caN be installed using NPM provides what you need:

https://github.com/oscmejia/os-utils

calle the cpuUsage(callback) method and you will get what you need.

If you are looking at the CPU Usage per process try node-usage

a simple hack:

var os = require('os')
var samples = []
var prevCpus = os.cpus()

setInterval(sample,100)
setInterval(print,1000)

function print() {
  var result = {last10:null, last50:null, last100:null}
  var percent = 0
  var i = samples.length
  var j = 0
  while (i--) {
    j++
    if (samples[i].total > 0)
      percent += (100 - Math.round(100 * samples[i].idle / samples[i].total))
    if (j == 10)       result.last10  = percent/j   
    else if (j == 50)  result.last50  = percent/j    
    else if (j == 100) result.last100 = percent/j
  }
  console.log(result)
}

function sample() {
  currCpus = os.cpus()
  for (var i=0,len=currCpus.length;i<len;i++) {
    var prevCpu = prevCpus[i]
    var currCpu = currCpus[i]
    var deltas = {total:0}
    for (var t in prevCpu.times) 
      deltas.total += currCpu.times[t] - prevCpu.times[t]
    for (var t in prevCpu.times) 
      deltas[t] = currCpu.times[t] - prevCpu.times[t]
  }
  prevCpus = currCpus
  samples.push(deltas)
  if (samples.length>100) samples.shift()
}

you could use a metrics-lib like https://github.com/felixge/node-measured to plumb something more prolific

This is my Solution

Interval is in Seconds.

10 will calculate load over the last 10 seconds!

var _  = require("underscore");
var os = require("os"); 
var interval = 1;
var old = _.map(os.cpus(),function(cpu){ return cpu.times;})

setInterval(function() {
    var result = [];
    var current = _.map(os.cpus(),function(cpu){ return cpu.times; })
    _.each(current, function(item,cpuKey){
        result[cpuKey]={}

        var oldVal = old[cpuKey];
        _.each(_.keys(item),function(timeKey){
            var diff = (  parseFloat((item[timeKey]) - parseFloat(oldVal[timeKey])) / parseFloat((interval*100)));
            var name = timeKey;
            if(timeKey == "idle"){
                name = "CPU"        
                diff = 100 - diff;
            }
            //console.log(timeKey + ":\t" + oldVal[timeKey] + "\t\t" + item[timeKey] + "\t\t" + diff);  
            result[cpuKey][name]=diff.toFixed(0);
        });
    });
    console.log(result);
    old=current;
}, (interval * 1000));

Outputs something like this on my 8-core every n-seconds

[ { user: '82', nice: '0', sys: '18', CPU: '100', irq: '0' },
  { user: '1', nice: '0', sys: '1', CPU: '3', irq: '0' },
  { user: '1', nice: '0', sys: '1', CPU: '3', irq: '0' },
  { user: '9', nice: '0', sys: '2', CPU: '11', irq: '0' },
  { user: '1', nice: '0', sys: '0', CPU: '1', irq: '0' },
  { user: '1', nice: '0', sys: '1', CPU: '2', irq: '0' },
  { user: '1', nice: '0', sys: '2', CPU: '2', irq: '0' },
  { user: '1', nice: '0', sys: '2', CPU: '3', irq: '0' } ]

Pushing this via socket.io into my Flow-Charts ;)

i'm using this code:

var cpu_used = function(){
var cpu = os.cpus();

var counter = 0;
var total=0;

var free=0;
var sys=0;
var user=0;

for (var i = 0; i<cpu.length ; i++) {

    counter++;
    total=parseFloat(cpu[i].times.idle)+parseFloat(cpu[i].times.sys)+parseFloat(cpu[i].times.user)+parseFloat(cpu[i].times.irq)+parseFloat(cpu[i].times.nice);

    free+=100*(parseFloat(cpu[i].times.idle)/total);
    sys+=100*(parseFloat(cpu[i].times.sys)/total);
    user+=100*(parseFloat(cpu[i].times.user)/total);
};

console.log('CPU %s : %s + %s + %s',i,(free/counter),(user/counter),(sys/counter));

}

If you want to watch real time CPU and memory usage, you can try os-usage.

The basic usage is like following:

var usage = require('os-usage');

// create an instance of CpuMonitor
var cpuMonitor = new usage.CpuMonitor();

// watch cpu usage overview
cpuMonitor.on('cpuUsage', function(data) {
    console.log(data);

    // { user: '9.33', sys: '56.0', idle: '34.66' }
});

You can also get processes that use most cpu resources:

cpuMonitor.on('topCpuProcs', function(data) {
    console.log(data);

    // [ { pid: '21749', cpu: '0.0', command: 'top' },
    //  { pid: '21748', cpu: '0.0', command: 'node' },
    //  { pid: '21747', cpu: '0.0', command: 'node' },
    //  { pid: '21710', cpu: '0.0', command: 'com.apple.iCloud' },
    //  { pid: '21670', cpu: '0.0', command: 'LookupViewServic' } ]
});

Here how I did it:

var OS = require('os');
var oldCPUTime = 0
var oldCPUIdle = 0
function getLoad(){
    var cpus = OS.cpus()
    var totalTime = -oldCPUTime
    var totalIdle = -oldCPUIdle
    for(var i = 0; i < cpus.length; i++) {
        var cpu = cpus[i]
        for(var type in cpu.times) {
            totalTime += cpu.times[type];
            if(type == "idle"){
                totalIdle += cpu.times[type];
            }
        }
    }

    var CPUload = 100 - Math.round(totalIdle/totalTime*100))
    oldCPUTime = totalTime
    oldCPUIdle = totalIdle

    return {
        CPU:CPUload,
        mem:100 - Math.round(OS.freemem()/OS.totalmem()*100)
    }       
}

来源：https://stackoverflow.com/questions/9565912/convert-the-output-of-os-cpus-in-node-js-to-percentage

标签

node.js

operating-system

cpu