Re: [PATCH] smp/call: Detect stuck CSD locks

[Ingo Molnar]

* Ingo Molnar <mingo@xxxxxxxxxx> 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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