Change affinity of process with windows script

Question

In Windows, with

 START /node 1 /affinity ff cmd /C "app.exe"

I can set the affinity of app.exe (number of cores used by app.exe).

With a windows script, How I can change the affinity of a running process ?

Answer 1

PowerShell can do this task for you

Get Affinity:

PowerShell "Get-Process app | Select-Object ProcessorAffinity"

Set Affinity:

PowerShell "$Process = Get-Process app; $Process.ProcessorAffinity=255"

Example: (8 Core Processor)

• Core # = Value = BitMask
• Core 1 = 1 = 00000001
• Core 2 = 2 = 00000010
• Core 3 = 4 = 00000100
• Core 4 = 8 = 00001000
• Core 5 = 16 = 00010000
• Core 6 = 32 = 00100000
• Core 7 = 64 = 01000000
• Core 8 = 128 = 10000000

Just add the decimal values together for which core you want to use. 255 = All 8 cores.

• All Cores = 255 = 11111111

Example Output:

C:\>PowerShell "Get-Process notepad++ | Select-Object ProcessorAffinity"

                                                              ProcessorAffinity
                                                              -----------------
                                                                            255



C:\>PowerShell "$Process = Get-Process notepad++; $Process.ProcessorAffinity=13"

C:\>PowerShell "Get-Process notepad++ | Select-Object ProcessorAffinity"

                                                              ProcessorAffinity
                                                              -----------------
                                                                             13



C:\>PowerShell "$Process = Get-Process notepad++; $Process.ProcessorAffinity=255"

C:\>

Source:

Here is a nicely detailed post on how to change a process's affinity: http://www.energizedtech.com/2010/07/powershell-setting-processor-a.html

Answer 2

The accepted answer works, but only for the first process in the list. The solution to that in the comments does not work for me.

To change affinity of all processes with the same name use this:

Powershell "ForEach($PROCESS in GET-PROCESS processname) { $PROCESS.ProcessorAffinity=255}"

Where 255 is the mask as given in the accepted answer.