I am running Fedora Core 4 2.6.16-1.2111 smp kernel on an aging 2 CPU Dell
PowerEdge 2300. I am attempting to resolve some issues I'm having with a PCI
device. I have changed many things (see posts to Asterisk users list
entitled "Audio problems on Zap & SIP, local network, not IRQ related?") and
am now trying to change the SMP affinity so that the PCI device (which is
using IRQ20) is handled solely by CPU1:
cat /proc/interrupts
CPU0 CPU1
0: 54233 51707 IO-APIC-edge timer
1: 1 7 IO-APIC-edge i8042
8: 0 1 IO-APIC-edge rtc
9: 0 0 IO-APIC-level acpi
16: 47254 46402 IO-APIC-level megaraid
17: 2169 1325 IO-APIC-level aic7xxx, aic7xxx
18: 305 13 IO-APIC-level eth0
19: 0 0 IO-APIC-level uhci_hcd:usb1
20: 25694 20011 IO-APIC-level wctdm
NMI: 0 0
LOC: 105840 105584
ERR: 0
MIS: 0
echo 2 > /proc/irq/20/smp_affinity
cat /proc/irq/20/smp_affinity
00000002
However I can see the interrupts for IRQ 20 are still incrementing on both
CPUs. Indeed, after about 10 seconds...
cat /proc/irq/20/smp_affinity
00000001
On further investigation, the SMP affinity on ALL of the IRQs is set to
00000001. This implies that everything is handled by CPU0, which it clearly
is not!
I wonder if anyone has experienced anything similar or could offer some
suggestions?
Regards
Cameron
