How could I know which core a process is running on?

问题

I am currently working on a project about setting process to one core in linux environment. I use sched_setaffinity to do this job and I wonder whether there are some functions provided by linux to get which core the process is running on. I use top command and find it could get this info using j option. So i am sure there are some ways to get this info in user space.

回答1:

You probably want sched_getcpu(). If you are running an older version of glibc, you can read the 39th field of /proc/[pid]/stat for the appropriate pid -- see the proc(5) man page for more details.

回答2:

You can use inline assembly (on a x86 arch) to achieve this:

mov eax, 1   ; cpuid functionality depends on the value of eax
cpuid        ; get cpu info
shr ebx, 24  ; ebx[31:24] is the cpu ID.
mov eax, ebx ; eax contains the cpu ID

you can read more about CPUID instruction here http://download.intel.com/design/processor/applnots/24161832.pdf

来源：https://stackoverflow.com/questions/3691331/how-could-i-know-which-core-a-process-is-running-on