JSI Tip 3542. How can I permanently set the processor affinity for an application?

In tip 0209, I describe how you can set the processor affinity on a running application.

In tip 2191, I described how bind devices to processors, to improve performance by more effectively using the processor's cache.

You can permanently set processor affinity for a non-operating system executable, on both Windows 2000 and Windows NT 4.0, by using the Imagecfg.exe tool from the \support\debug\i386 folder of a Windows NT 4.0 CD-ROM, or the Imagecfg.exe tool from the Windows 2000 Server Resource Kit Supplement One.

NOTE: Do NOT use imagecfg on any kernel operating system files.

To permanently set the processor affinity for your 32-bit executable, open a CMD prompt and type:

imagecfg -a 0xn <Drive:>\Path\yourprogram.exe

where 0xn is the affinity mask. The mask constrains your application to a specific CPU, from 0 - 31, where:

  0    0x1
  1    0x2
  2    0x4
  3    0x8
  4    0x10
  5    0x20
  6    0x40
  7    0x80
  8    0x100
To set the affinity for "c:\util\Country Codes.exe" to processor 1, I typed:

imagecfg -a 0x2 "c:\util\Country Codes.exe"

and received the following response:

c:\util\Country Codes.exe contains no configuration information
c:\util\Country Codes.exe contains a Subsystem Version of 4.0
c:\util\Country Codes.exe updated with the following configuration information:
    Process Affinity Mask: 00000002
When I launch Country Codes.exe, its' affinity is set to CPU 1.

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