The interface introduces a sys_perf_event_open() syscall, with the counters being started and stopped using ioctls, and read either with read() calls or mmapping samples into circular buffers. The perf_event_open() syscall is defined as follows:

#include <linux/perf_event.h> 
#include <linux/hw_breakpoint.h> 
 
int perf_event_open(struct perf_event_attr *attr, 
                    pid_t pid, int cpu, int group_fd, 
                    unsigned long flags); 

There is no C library wrapper for it, so it needs to be called using syscall().