[Asterisk-Users] Does use of riser cards in racks affects performance of PCI telephony cards ?

[Andrew Kohlsmith]

On October 21, 2004 08:06 am, Robert Rozman wrote:
> I don't know much about HW, but would like to know if I use riser card
> (vertical adapter for 1-3 PCI cards that goes into one PCI slot) to put
> some Asterisk HW cards on it in rack chassis - do I affect their
> performance in regard of interrupt priority latency in comparison with
> normal placing of each card in separate PCI slot?

Each PCI slot has four interrupt pins.  Unless the riser card is shuffling 
these pins around like a normal PCI motherboard does, all the cards on the 
riser will share the same interrupt.

It's my understanding that part of the PCI spec is that any card should be 
able to use INTA-D as its primary interrupt source but I've never seen a card 
that actually lets you choose which interrupt line to use, in hardware or in 
the driver.  Pity, really.

-A.