[asterisk-users] Re: Dell PowerEdge 2950 Sharing NIC IRQ with Digium Card

[Remco Barendse]

On Sun, 11 Feb 2007, Leo Ann Boon wrote:

> Matt wrote:
>>
>>  I guess the question is... is it even possible to have a real-time VoIP
>>  card running on PCIe?  Or with 1,000 Interrupts a second.. does it simply
>>  need to have its own IRQ?
> Have you tried the Sangoma PCIe cards?
>
> APIC is supposed to fixed the PCI IRQ problem. AFAIK, APIC is not a virtual 
> interrupt. It requires an additional interrupt controller to deal with the 
> additional interrupt lines. The BIOS cannot see it because it's still stuck 
> with the 8086 15-interrupt mindset. When you run a modern OS like Windows XP 
> and Linux, the OS can will make the CPU aware of the additional interrupts 
> from the secondary interrupt controllers. At the BIOS level, you'll see 
> 'shared' interrupts for APIC system because the mobo designer need to cascade 
> the new interrupt controller to the standard controller. Otherwise, the 
> interrupts from the secondary controller will not be available to real-mode 
> applications.

If the above would work like it was meant to be why do many cards still 
have irq problems?  In zttest i only get 99.987793% scores, not higher, 
not lower only a very rare 100%.

My cheap ass Asus A78VX-X board scores considerably better then this 
expensive Dell machine with the same Digium card and software installed.

I have apic enabled, disabling apic from the kernel did not help to 
improve things

My simple conclusion from the above is that the Dell hardware sucks.

result from zttest :
--- Results after 198 passes ---
Best: 100.000000 -- Worst: 99.987793 -- Average: 99.988498

[root at pbx zaptel-1.2.13]# cat /proc/interrupts
            CPU0
   0:   82179609    IO-APIC-edge  timer
   2:          0          XT-PIC  cascade
   8:          1    IO-APIC-edge  rtc
  14:     738454    IO-APIC-edge  ide0
  74:   82142210   IO-APIC-level  wct2xxp
201:     745906   IO-APIC-level  megaraid
209:     137704   IO-APIC-level  eth0
217:     177366   IO-APIC-level  eth1
NMI:          0
LOC:   82178536
ERR:          0
MIS:          0