Duration of Blocked Interrupts

[Doug Ledford]

Matthew Jacob wrote:
> 
> Yes, this might be true. The only problem here is that in
> looking over the version of the linux AIC stuff I have,
> it *does* go to the effort to restore_flags in a number
> of places so it doesn't lock out *everyone* for long periods
> of time. That is, it locks out all interrupts briefly
> (mostly to mark that it's servicing an interrupt), and
> then it runs a while w/o. It blocks interrupts checking
> for sequencer conditions (usually error cases), and also
> while cleaning up after finishing. It then unblocks
> interrupts before calling the linux midlayer to complete
> (well done, actually).
> 
> By "blocking/unblocking" I mean higher level interrupts.
> I could easily believe that if your network cards are
> at lower or same irqs they might starve. But short
> of doing some more clever thread managment, or doing
> an explicit sti() in the SCSI midlayer, I doubt that this
> is easily fixable.

I did change that in the later versions of my code.  For 2.1.x, it is
specifically required that we *don't* enable interrupts during completion
processing.  I could put it back for 2.0.x, but it would create a few
questions on my part until I've had time to fully verify everything does
what it's suppossed to do.

-- 

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

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