Re: linux interrupt handling problem

yodaiken@chelm.cs.nmt.edu
Wed, 10 Nov 1999 08:54:30 -0700

On Wed, Nov 10, 1999 at 11:30:53AM +0100, Roman Zippel wrote:
> That's a problem I would like to address later, since it's a perfomance
> only problem, where the sti() stuff is also a portability problem.
> Anyway, I'm preparing some stuff to address this, but that's the more
> complex change, but I hope to get a better overall perfomance out of
> this, as there are more perfomance problems with some linux interrupt
> handler (especially almost all block devices).

Any measurements to show that this is a real problem? My intuition
is that the simple Linux model has enormous advantages over
more complex schemes. For one thing, using irq levels makes it
very easy to introduce impossible to find synchronization bugs.
Down in the interior of the scsi code, someone uses the wrong irq
level and the serial driver starts dropping bytes every now and
then. For another, RTLinux depends on a Linux to have a sensible
and clear interrupt model. I very much doubt we could have
made RTLinux work if Linux was trying to be too clever about
interrupt priorities etc.

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