perf源码解析

kernel-reading

perf stat -e cache-misses -I 1000 -p 2197

sys_perf_event_open

• http://man7.org/linux/man-pages/man2/perf_event_open.2.html
• http://ozlabs.org/~anton/junkcode/perf_events_example1.c
• http://hchen229.iteye.com/blog/585434
• https://blog.csdn.net/u012884354/article/details/45720737

code: sys_perf_event_open
- https://www.processon.com/view/58a55155e4b0669d9942fdbe

static int perf_event_read_one(struct perf_event *event,
                 u64 read_format, char __user *buf)
{
    u64 enabled, running;
    u64 values[4];
    int n = 0;
    values[n++] = perf_event_read_value(event, &enabled, &running);
    printk("<0>""liujunming  perf_event_read_one value%llu\n", values[0]);
    if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
        values[n++] = enabled;
    if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
        values[n++] = running;
    if (read_format & PERF_FORMAT_ID)
        values[n++] = primary_event_id(event);
    if (copy_to_user(buf, values, n * sizeof(u64)))
        return -EFAULT;
    return n * sizeof(u64);
}