I have already written about how to use processor affinity to restrict a process and run it only on a specified central processing unit (CPU) under Linux.
This document talks about setting Processor affinity on AIX.
From the article:
Processor affinity is a facility provided by operating systems, and you can use it on multi-processor hardware. All the threads within the process can be bound to run on the specified processor. Using process affinity settings to bind or unbind threads can help you find the root cause of troublesome hang or deadlock problems, especially for those hairy deadlocks and hangs that are hard to debug.
Regardless of what system you use and what functional and regression testing you do when your application is deployed for production, you can still get errors that are unavoidable. You might get a hang where the CPU is being used 100 percent of the time, or you might get deadlocks where a couple of threads are locked and never release a resource. In some cases, you'll see hangs in the application that are very old (even a couple of decades back), even on multiprocessor architectures and fast hardware.
Processor affinity on AIX [ibm.com]