* Ingo Molnar <mi...@kernel.org> wrote:

> +static void csd_lock_wait(struct call_single_data *csd, int cpu)
>  {
> -     while (csd->flags & CSD_FLAG_LOCK)
> +     int bug_id = 0;
> +     u64 ts0, ts1, ts_delta;
> +
> +     ts0 = jiffies_to_msecs(jiffies);

Note that while 'jiffies' is a global variable, it's read-mostly 
accessed, so it is a pretty cheap way to acquire a timestamp in such a 
simple polling context that has irqs enabled.

Thanks,

        Ingo
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