I have a machine running Centos 5, x86_64.

It has an Intel NIC:

# lspci 15:00.0 Ethernet controller: Intel Corporation 82572EI Gigabit Ethernet Controller (Fiber) (rev 06)

The machine has two dualcore cpus.

If I look at /proc/interrupts I get:

CPU0 CPU1 CPU2 CPU3 0: 144873228 220741831 173615012 220733357 IO-APIC-edge timer 4: 269120 1203485 1964914 1528555 IO-APIC-edge serial 7: 0 0 0 0 IO-APIC-edge parport0 8: 0 0 0 0 IO-APIC-edge rtc 9: 0 0 0 0 IO-APIC-level acpi 14: 137 3218764 3143397 430444 IO-APIC-edge ide0 90: 3403812 5504380 553784 1273225 IO-APIC-level aic79xx 98: 460440049 0 0 0 PCI-MSI eth0 169: 210489 9211230 26272710 31733980 IO-APIC-level uhci_hcd:usb2, uhci_hcd:usb3, aacraid 177: 0 0 0 0 IO-APIC-level uhci_hcd:usb4 185: 2 0 0 0 IO-APIC-level uhci_hcd:usb1, ehci_hcd:usb5 NMI: 359 102 105 115 LOC: 744651234 743298229 744651090 743298086 ERR: 0 MIS: 0

My question is: Why are the eth0 interrupts distributed to CPU0 only?

Mogens