如何在ARM Cortex-A8处理器中测量程序执行时间？

#include<stdio.h>
#include <time.h>

int main() {
    clock_t start = clock();
    // 要执行的代码
    clock_t end = clock();
    double elapsed_secs = (double)(end - start) / CLOCKS_PER_SEC;
    printf("程序执行时间：%f秒\n", elapsed_secs);
    return 0;
}

#include<stdio.h>
#include <sys/time.h>

int main() {
    struct timeval start, end;
    gettimeofday(&start, NULL);
    // 要执行的代码
    gettimeofday(&end, NULL);
    double elapsed_secs = (end.tv_sec - start.tv_sec) + (end.tv_usec - start.tv_usec) / 1000000.0;
    printf("程序执行时间：%f秒\n", elapsed_secs);
    return 0;
}

#include<stdio.h>
#include <time.h>

int main() {
    time_t start = time(NULL);
    // 要执行的代码
    time_t end = time(NULL);
    double elapsed_secs = difftime(end, start);
    printf("程序执行时间：%f秒\n", elapsed_secs);
    return 0;
}

#include<stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include<linux/perf_event.h>

int main() {
    struct perf_event_attr attr;
    long long count;
    int fd;

    memset(&attr, 0, sizeof(attr));
    attr.type = PERF_TYPE_HARDWARE;
    attr.config = PERF_COUNT_HW_CPU_CYCLES;
    attr.exclude_kernel = 1;
    attr.exclude_hv = 1;

    fd = perf_event_open(&attr, 0, -1, -1, 0);
    if (fd == -1) {
        perror("perf_event_open");
        exit(EXIT_FAILURE);
    }

    ioctl(fd, PERF_EVENT_IOC_RESET, 0);
    ioctl(fd, PERF_EVENT_IOC_ENABLE, 0);

    // 要执行的代码

    ioctl(fd, PERF_EVENT_IOC_DISABLE, 0);
    read(fd, &count, sizeof(count));

    printf("程序执行时间：%lld秒\n", count);

    close(fd);
    return 0;
}