[Techtalk] Who Knows IRQ

coldfire rolick571 at duq.edu
Wed Aug 21 01:54:39 EST 2002

> > Hi People,
> > 
> > 	Just a quick question or three about IRQ.
> > 
> > 	What is it?
> > 	Should *four* ON-board devices have the same IRQ? IRQ11,= 
> > ethernet,usb,usb, multimedia.
> IRQ is an Interrupt ReQuest line.  Basically, you used to only have one
> device on each one, and that was its main way to talk to the CPU.  If
> your machine had lots of devices, you ended up in IRQ hell, where
> devices all wanted the same IRQ and some would not work.
> By no means a hardware expert, but friends who are tell me that modern
> machines have "PCI steering" so they can handle a bunch of devices on
> one IRQ.  Of course, these folks only run Varieties of Windows, so I do
> not know for sure if that carries over to the Linux world :)

i'd just like to add .. that back in the days when windows 98 existed on
my machine, i had a scsi card and network card that always fought for the
same irq.  sometimes the network wouldn't work, other times i couldn't
access my cdr drive. hell, sometimes it wouldn't boot.  but in linux,
everything always worked fine .. if there were performance issues, i
couldn't say.  never noticed horrible performance so i never worried about
checking.  :)


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