Re: rate limiting error messages

[Khalid Aziz <khalid@fc.hp.com>]

Eli Carter wrote:
> 
> Can someone point me to a "standard way" of doing rate limiting of error
> messages in the kernel?
> 
> TIA,
> 
> Eli
> -----------------------.           Rule of Accuracy: When working toward
> Eli Carter             |            the solution of a problem, it always
> eli.carter(at)inet.com `------------------ helps if you know the answer.

Here is how it is done in IA-64 kernel:

static int
within_logging_rate_limit (void)
{
        static unsigned long count, last_time;

        if (count > 5 && jiffies - last_time > 5*HZ)
                count = 0;
        if (++count < 5) {
                last_time = jiffies;
                return 1;
        }
        return 0;

}

If this fundction returns 0, error messages have been rate limited. This
code is not MP-safe. So, if you need your code to be MP-safe, you may
need to rewrite it somewhat.

-- 
Khalid

====================================================================
Khalid Aziz                             Linux Development Laboratory
(970)898-9214                                        Hewlett-Packard
khalid@fc.hp.com                                    Fort Collins, CO