Duration of Blocked Interrupts

[Doug Ledford]

Mail Receiver wrote:
> 
> We're doing some research into what parts of the Linux kernel block
> interrupts for the longest periods of time (as part of a real-time
> project).  Surprise, surprise, we found the disk subsystem to be one of
> the biggest contributors.  In particular, we've found that the aic7xxx_isr
> routine can block interrupts for periods of as long as 400+ microseconds

What version of the aic7xxx driver were you testing?  I wouldn't be suprised
if the latest versions can do exactly this.  There are things that can be
done to get around this problem in 2.0.x, but there won't be much we can do
about it at all in 2.1.x and probably 2.2.x due to the spin lock semantics
and requirements.  I would have to consider the consequences of changing
things around in the 2.1.x driver before I would recommend the changes I'm
thinking of.

-- 

 Doug Ledford  <dledford at dialnet.net>
  Opinions expressed are my own, but
     they should be everybody's.

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