Missing C functions getcpu() and sched_getcpu() (Deprecated?)


Are the C functions sched_getcpu() and getcpu() deprecated in Leap 15.1?
Because I can’t find them on my system. But the man-pages exists for these functions.

Always get the following compiler warning:

$ gcc -o test main.c
main.c: In function ‘main’:
main.c:9:33: warning: implicit declaration of function ‘sched_getcpu’; did you mean ‘sched_getparam’? -Wimplicit-function-declaration]
     printf("CPU: %d
", sched_getcpu());

Here the code:

#include <stdio.h>
#include <sched.h>

int main(int argc, char *argv])
    printf("CPU: %d
", sched_getcpu());

As is quite clearly documented in sched_getcpu man page, you need _GNU_SOURCE macro to enable its definition.

P.S. and how is this question related to Install/Boot/Login?