How to Get the Number of CPU Cores in .NET/C#?

Retrieving CPU Core Count using .NET/C#

.NET/C# provides several methods for identifying the number of CPU cores available on a system. Here are a few approaches:

1. Physical Processors:

This method counts the number of physical processors installed.

foreach (var item in new System.Management.ManagementObjectSearcher("Select * from Win32_ComputerSystem").Get())
{
    Console.WriteLine($"Number of Physical Processors: {item["NumberOfProcessors"]}");
}

2. Cores per Processor:

This approach sums the core count across all processors.

int totalCores = 0;
foreach (var item in new System.Management.ManagementObjectSearcher("Select * from Win32_Processor").Get())
{
    totalCores += int.Parse(item["NumberOfCores"].ToString());
}
Console.WriteLine($"Total Number of Cores: {totalCores}");

3. Logical Processors:

This directly accesses the total number of logical processors (including hyperthreading).

Console.WriteLine($"Number of Logical Processors: {Environment.ProcessorCount}");

4. Processors (excluding those hidden by Windows):

This method accounts for processors that might be excluded from standard Windows reporting. It requires using the Setup API.

int processorCount = 0;
IntPtr deviceList = IntPtr.Zero;
Guid processorGuid = new Guid("{50127dc3-0f36-415e-a6cc-4cb3be910b65}");

try
{
    deviceList = SetupDiGetClassDevs(ref processorGuid, "ACPI", IntPtr.Zero, (int)DIGCF.PRESENT);
    for (int deviceNumber = 0; ; deviceNumber++)
    {
        SP_DEVINFO_DATA deviceInfo = new SP_DEVINFO_DATA();
        deviceInfo.cbSize = Marshal.SizeOf(deviceInfo);
        if (!SetupDiEnumDeviceInfo(deviceList, deviceNumber, ref deviceInfo))
        {
            processorCount = deviceNumber;
            break;
        }
    }
}
finally
{
    if (deviceList != IntPtr.Zero) { SetupDiDestroyDeviceInfoList(deviceList); }
}
Console.WriteLine($"Number of Cores (including hidden): {processorCount}");

Important Considerations:

• System.Management.dll: Remember to add a reference to System.Management.dll in your project.
• System Updates: Complete system updates (hotfixes and service packs) may be necessary for accurate results on some systems. The availability of detailed processor information depends on the system's configuration and updates.

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