From: "Sean Akers"
Message-ID: <80256992.005D90B8.00@romaxtech.com>
Date: Thu, 9 Nov 2000 17:12:02 +0000
Subject: Re: [SLE] IRQ sharing
<p><p><p>Sean Akers@ROMAX
09/11/2000 17:12
AFAIK, the PCI hardware standard requires that all PCI cards MUST be able
to share IRQs. I've never seen Linux share PCI IRQs though. Windows 2000
makes use of this requirement to a fault in fact. In every Windows 2000
I've installed, it puts just about every PCI device at the same IRQ whether
you want it to or not. On my W2K system at home, the video, network, sound
and Promise Ultra/66 cards all share the same IRQ (and there's no way of
changing this either which gets right up my nose). I'm sure it would be
more efficient to spread these devices over all the available IRQs and only
double up when you've run out after all, the OS must be doing some sort of
polling when it gets an interrupt on a shared IRQ to find out which device
needs servicing.
My SuSE 6.4 Linux server has 2 PCI network cards, a PCI SCSI card and a PCI
video card. All are automatically put on different IRQs. Perhaps someone
can tell us about IRQ sharing under Linux in more details but I expect it
does it the sensible way by spreading things out as much as possible.
Sean.
