CODEWITHSUNDEEP
clinuxprocesssmp
terry
terry

Reputation: 1497

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

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.

Upvotes: 4

Views: 2648

Answers (2)

llasram
llasram

Reputation: 4475

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.

Upvotes: 5

AmirW
AmirW

Reputation: 816

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

Upvotes: 1

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