How can I get CPU load per core in C#?

Question

Hi,

How can I get CPU Load per core (quadcore cpu), in C#?

Thanks :)

Answer 1

Since cores show up as seperate CPUs to the OS, you use the same code you'd use to determine the load per CPU in a multiprocessor machine. One such example (in C) is here. Note that it uses WMI, so the other thread linked in the comments above probably has you most of the way there.

Answer 2

You can either use WMI or the System.Diagnostics namespace. From there you can grab any of the performance counters you wish (however it takes a second (1-1.5s) to initialize those - reading values is ok, only initialization is slow)

Code can look then like this:

    using System.Diagnostics;

    public static Double Calculate(CounterSample oldSample, CounterSample newSample)
    {
        double difference = newSample.RawValue - oldSample.RawValue;
        double timeInterval = newSample.TimeStamp100nSec - oldSample.TimeStamp100nSec;
        if (timeInterval != 0) return 100*(1 - (difference/timeInterval));
        return 0;
    }

    static void Main()
    {
        var pc = new PerformanceCounter("Processor Information", "% Processor Time");
        var cat = new PerformanceCounterCategory("Processor Information");
        var instances = cat.GetInstanceNames();
        var cs = new Dictionary<string, CounterSample>();

        foreach (var s in instances)
        { 
            pc.InstanceName = s;
            cs.Add(s, pc.NextSample());
        }

        while (true)
        {
            foreach (var s in instances)
            {
                pc.InstanceName = s;
                Console.WriteLine("{0} - {1:f}", s, Calculate(cs[s], pc.NextSample()));
                cs[s] = pc.NextSample();
            }
            System.Threading.Thread.Sleep(500);
        }
    }

Important thing is that you cant rely on native .net calculation for 100nsInverse performance counters (returns only 0 or 100 for me ... bug?) but you have to calculate it yourself and for that you need an archive of last CounterSamples for each instance (instances represent a core or a sum of those cores).

There appears to be a naming convetion for those instances :

0,0 - first cpu first core 0,1 - first cpu second core 0,_Total - total load of first cpu _Total - total load of all cpus

(not verified - would not recommend to rely on it untill further investigation is done)...