disabling interrupt storm protection

[John Baldwin]

On Friday 29 October 2004 11:37 pm, Shunsuke SHINOMIYA wrote:
>  Thank you John,
>
>  I wrote a patch(which is attached to this mail) so that the problem
>  doesn't occur in my environment.
>
>  This patch changes the meaning of `storm'.
>  But, I think use of the parameter(hw_intr_threshold) to control the
> detector in this method is clearer than the present method, and it
> needs no DELAY(1).
>
>  In the detector to which this patch is applied and compiled with
>  -DHACK2 flag, `storm' is the situation that the number of generated
>  interrupts per unit time(1/hz) is larger than threshold.
>
>  If kern_intr.c is compiled with -DHACK2 -DHACK3 flags, it works as
>  interrupt rate limiter.
>
>  What do you think about this method?

A true interrupt storm that is trying to be handled here is not necessarily a 
high rate of interrupts (that can just be high load, but that is ok), but 
instead when a level triggered interrupt isn't handled it ends up firing 
again as soon as you re-enable interrupts.  The goal is to at least give the 
system some time to run with the constantly interrupting source disabled so 
that other work can be done.

-- 
John Baldwin <jhb at FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve"  =  http://www.FreeBSD.org