irq question

[Oliver Fromme]

John Baldwin <jhb at freebsd.org> wrote:
 > Zoran Kolic wrote:
 > > Dear all!
 > > For next week or two, I'll get
 > > cable net; for nforce3 mobo I
 > > put "rl" card into the last
 > > pci slot. At least I am aware
 > > of some possible irq mess with
 > > that.
 > > Here is information from dmesg:
 > >   ehci0 irq 10 at device 2.2 on pci0
 > >   atapci1 irq 10 at device 10.0 on pci0
 > >   rl0 irq 10 at device 10.0 on pci2
 > > Does it mean that I should wait and
 > > see? Or change the place in advance?
 > > Motherboard has 5 pci slots (asus
 > > k8n).
 > > I would like to not be told by
 > > service folks to install win to
 > > have the system work properly.
 > > Best regards
 > 
 > What specific problem are you having?  Does the rl0 card not work?

I think he is concerned about irq10 shared between three
devices (ehci0, atapci1, rl0).

While in theory irq sharing should work fine, it can come
with a noticeable performance penalty.  In particular, the
ehci interrupt handler is pretty heavy-weight and might
slow rl0 down.  (rl(4) isn't one of the best performers
anyway.)

I've seen such cases in the i386 world, and the solution
was to disable USB completely and not load the driver
(USB wasn't needed on those machines).  Another way is
to have a look at the BIOS setup.  Some of them still
offer the ability to manually configure the interrupts.

Best regards
   Oliver

-- 
Oliver Fromme,  secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing
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