How to set processor affinity on an executable in Windows XP


I have a quad core system with third party application that once in a while spins several processes (always the same executable but several instances of it) and takes 100% of CPU time. I also have a couple of web services running on the same box (IIS and third party).

The problem with the all cores being busy is that it makes this third party web server to timeout (IIS works fine though, just slower than usual). I have no control over third party web server, it's a part of the bigger product and has to be operational. So, I tried to play with processor affinity (via SysInternals Process Explorer) and limit those pesky processes to 3 cores out of 4 and dedicate the 4th core to the third party web server, and it seems to work quite well.

The problem is that it only sets affinity on the running process and not on executable level, so after those processes finish and later respawn as a new processes it's all the same again – they take all 4 cores. So, I've googled about this ImageCfg.exe utility from Microsoft but I can't find it on Microsoft webside for download and I see that some people tried it and now complain that it doesn't really work.

Is there a way to stick the affinity to the executable?

Best Solution


Use PowerShell to set the processor affinity for one or more running processes. There’s an example script below, setting the processor mask of calc.exe to the first 4 processors. I like this method because the script is simple, it would be easy to schedule, works on x86 and x64, supports multiple processes of the same name and at least partly because it highlights just how easy administration with PowerShell is.

Note that if you use factorial of a large number with calc.exe (n!) you’ll generate100% CPU which can be useful for testing. The mask below is 0xf = 1111 – a mask allowing use of only the first four processors:

$calcSet = Get-Process -ProcessName "calc"
foreach ($calc in $calcSet) {$calc.ProcessorAffinity=0xF}
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