Re: 3 PCI NIC's on OpenBSD 2.6(x86) sharing IRQ's

[Seth Arnold <sarnold@willamette.edu>]

* Steve Williams <steve@genie96.com> [001116 16:37]:
> Humm... I haven't done hardware since back in the "old" days, when it
> was critical that nothing share IRQ's.
> 
> Is this still the case?

I think it is common for devices to share IRQs, though it will adversely
effect performance in some cases. So, if your machine needs to perform
wonderfully, try to change this. If you machine sees only occasional
packets (as mine does) then maybe it isn't worth your time to fix it.
But, if you want speeds roughly equivalent to the max speeds the NICs
can do, then it might not hurt to try to seperate them a bit.

> fxp0 at pci0 dev 13 function 0 "Intel 82557" rev 0x05: irq 11, address ...
> fxp1 at pci0 dev 15 function 0 "Intel 82557" rev 0x05: irq 9, address ...
> fxp2 at pci0 dev 17 function 0 "Intel 82557" rev 0x08: irq 11, address ...

Hmm. I seem to recall that IRQ 9 was used for 'cascade', with IRQ 2.
(This thinking is from the "old" days as well, maybe this has changed
since then.)

If you go to the trouble of making each NIC have its own IRQ, see if you
can get the IRQ 9 NIC onto another IRQ as well.

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