How to get the CPU Usage in C#?

Question

You can use the PerformanceCounter class from System.Diagnostics.

Initialize like this:

PerformanceCounter cpuCounter;
PerformanceCounter ramCounter;

cpuCounter = new PerformanceCounter("Processor", "% Processor Time", "_Total");
ramCounter = new PerformanceCounter("Memory", "Available MBytes");

Consume like this:

public string getCurrentCpuUsage(){
            return cpuCounter.NextValue()+"%";
}

public string getAvailableRAM(){
            return ramCounter.NextValue()+"MB";
} 

A little more than was requsted but I use the extra timer code to track and alert if CPU usage is 90% or higher for a sustained period of 1 minute or longer.

public class Form1
{

    int totalHits = 0;

    public object getCPUCounter()
    {

        PerformanceCounter cpuCounter = new PerformanceCounter();
        cpuCounter.CategoryName = "Processor";
        cpuCounter.CounterName = "% Processor Time";
        cpuCounter.InstanceName = "_Total";

                     // will always start at 0
        dynamic firstValue = cpuCounter.NextValue();
        System.Threading.Thread.Sleep(1000);
                    // now matches task manager reading
        dynamic secondValue = cpuCounter.NextValue();

        return secondValue;

    }


    private void Timer1_Tick(Object sender, EventArgs e)
    {
        int cpuPercent = (int)getCPUCounter();
        if (cpuPercent >= 90)
        {
            totalHits = totalHits + 1;
            if (totalHits == 60)
            {
                Interaction.MsgBox("ALERT 90% usage for 1 minute");
                totalHits = 0;
            }                        
        }
        else
        {
            totalHits = 0;
        }
        Label1.Text = cpuPercent + " % CPU";
        //Label2.Text = getRAMCounter() + " RAM Free";
        Label3.Text = totalHits + " seconds over 20% usage";
    }
}

After spending some time reading over a couple different threads that seemed pretty complicated I came up with this. I needed it for an 8 core machine where I wanted to monitor SQL server. For the code below then I passed in "sqlservr" as appName.

private static void RunTest(string appName)
{
    bool done = false;
    PerformanceCounter total_cpu = new PerformanceCounter("Process", "% Processor Time", "_Total");
    PerformanceCounter process_cpu = new PerformanceCounter("Process", "% Processor Time", appName);
    while (!done)
    {
        float t = total_cpu.NextValue();
        float p = process_cpu.NextValue();
        Console.WriteLine(String.Format("_Total = {0}  App = {1} {2}%\n", t, p, p / t * 100));
        System.Threading.Thread.Sleep(1000);
    }
}

It seems to correctly measure the % of CPU being used by SQL on my 8 core server.

It's OK, I got it! Thanks for your help!

Here is the code to do it:

private void button1_Click(object sender, EventArgs e)
{
    selectedServer = "JS000943";
    listBox1.Items.Add(GetProcessorIdleTime(selectedServer).ToString());
}

private static int GetProcessorIdleTime(string selectedServer)
{
    try
    {
        var searcher = new
           ManagementObjectSearcher
             (@"\\"+ selectedServer +@"\root\CIMV2",
              "SELECT * FROM Win32_PerfFormattedData_PerfOS_Processor WHERE Name=\"_Total\"");

        ManagementObjectCollection collection = searcher.Get();
        ManagementObject queryObj = collection.Cast<ManagementObject>().First();

        return Convert.ToInt32(queryObj["PercentIdleTime"]);
    }
    catch (ManagementException e)
    {
        MessageBox.Show("An error occurred while querying for WMI data: " + e.Message);
    }
    return -1;
}

You can use WMI to get CPU percentage information. You can even log into a remote computer if you have the correct permissions. Look at http://www.csharphelp.com/archives2/archive334.html to get an idea of what you can accomplish.

Also helpful might be the MSDN reference for the Win32_Process namespace.

See also a CodeProject example How To: (Almost) Everything In WMI via C#.

CMS has it right, but also if you use the server explorer in visual studio and play around with the performance counter tab then you can figure out how to get lots of useful metrics.

This class automatically polls the counter every 1 seconds and is also thread safe:

public class ProcessorUsage
{
    const float sampleFrequencyMillis = 1000;

    protected object syncLock = new object();
    protected PerformanceCounter counter;
    protected float lastSample;
    protected DateTime lastSampleTime;

    /// <summary>
    /// 
    /// </summary>
    public ProcessorUsage()
    {
        this.counter = new PerformanceCounter("Processor", "% Processor Time", "_Total", true);
    }

    /// <summary>
    /// 
    /// </summary>
    /// <returns></returns>
    public float GetCurrentValue()
    {
        if ((DateTime.UtcNow - lastSampleTime).TotalMilliseconds > sampleFrequencyMillis)
        {
            lock (syncLock)
            {
                if ((DateTime.UtcNow - lastSampleTime).TotalMilliseconds > sampleFrequencyMillis)
                {
                    lastSample = counter.NextValue();
                    lastSampleTime = DateTime.UtcNow;
                }
            }
        }

        return lastSample;
    }
}