[linux-audio-user] APIC is bad?

[Jan Depner]

On Sat, 2004-07-17 at 06:33, Malcolm Baldridge wrote:
> > Slight side issue, while you guys are on the subject.
> > 
> > I have my soundcard (an onboard i8x0) sharing an interrupt (IRQ 11) with
> > eth0 and usb-uhci. Would this be likely to give rise to xruns in a 
> > similar way? 
> 
> I think motherboard audio bugs/latency issues will be more of a problem than
> shared IRQs.  Turning off the PnP Setting in the BIOS and then "Reset
> Configuration Data" may cause a re-assignment to occur during the next time
> you go through BIOS POST.
> 
> > or is it just a question of physically moving the ethernet card? 
> 
> Moving the ethernet card should get you another IRQ, though keep in mind,
> it's a bit stranger with PCI than ISA.  To make it even spicier, some PCI
> slots are not capable of bus-mastering DMA.  But the answer to your question
> is yes: moving the card will get you a different IRQ.
> 

	It may take a few tries to get everything where you want it though.


> As for the onboard-USB, well, that might be harder to "move".  The problem
> is that the IRQs are "mapped" to PCI INT-levels, and it seems that many
> system hardware designers get very lazy and slopping with how they use them.
> 
> Shared IRQs have been with us for a few years now, and I doubt it's the
> source of most xruns people see on their systems these days.  We are talking
> about microseconds of additional time to determine the interrupt source
> here.  If your xruns are in the hundreds of milliseconds, this is not your
> problem.  If you're on the borderlines, THEN it might be something worth
> looking into.
> 
	In addition to the time to determine interrupt source there is another
problem with shared interrupts - don't use any USB devices or run your
network while trying to record.


Jan