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ProcessThread.IdealProcessor Property

Sets the preferred processor for this thread to run on.

Namespace:  System.Diagnostics
Assembly:  System (in System.dll)

public int IdealProcessor { set; }

Property Value

Type: System.Int32
The preferred processor for the thread, used when the system schedules threads, to determine which processor to run the thread on.


The system could not set the thread to start on the specified processor.


The platform is Windows 98 or Windows Millennium Edition.


The process is on a remote computer.

The IdealProcessor value is zero-based. In other words, to set the thread affinity for the first processor, set the property to zero.

The system schedules threads on their preferred processors whenever possible.

A process thread can migrate from processor to processor, with each migration reloading the processor cache. Specifying a processor for a thread can improve performance under heavy system loads by reducing the number of times the processor cache is reloaded.

The following example demonstrates how to set the IdealProcessor property for an instance of Notepad to the first processor.

using System;
using System.Diagnostics;

namespace ProcessThreadIdealProcessor
    class Program
        static void Main(string[] args)
            // Make sure there is an instance of notepad running.
            Process[] notepads = Process.GetProcessesByName("notepad");
            if (notepads.Length == 0)
            ProcessThreadCollection threads;
            //Process[] notepads; 
            // Retrieve the Notepad processes.
            notepads = Process.GetProcessesByName("Notepad");
            // Get the ProcessThread collection for the first instance
            threads = notepads[0].Threads;
            // Set the properties on the first ProcessThread in the collection
            threads[0].IdealProcessor = 0;
            threads[0].ProcessorAffinity = (IntPtr)1;

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1
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