Do the changes to cpumask using sched_setaffinity() take place immediately

Question

I am writing a linux kernel module that needs to pin two threads on two different cpus. I am planning to use sched_setaffinity() after exporting it in the kernel. Is there any other exported function for the same ?

Also, if I set only 1 CPU in the cpumask, will the thread be moved to that cpu with immediate effect ? If not, how do I enforce the same ? Will it help to call schedule() just after sched_setaffinity() ?

Answer 1

The man page for sched_setaffinity says

If the process specified by pid is not currently running on one of the CPUs specified in mask, then that process is migrated to one of the CPUs specified in mask.

My intepretation is that this migration happens immediately, before the call to sched_setaffinity has returned.