Hi,
I'm not subscribed to the list, please cc me on replies.
I have a CentOS 7 linux system with 48 logical CPUs and a number of
Intel NICs running the i40e driver. It was booted with
irqaffinity=0-1,24-25 in the kernel boot args, resulting in
/proc/irq/default_smp_affinity showing "0000,03000003". CPUs 2-11 are
set as "isolated" in the kernel boot args. The irqbalance daemon is not
running.
The problem I'm seeing is that /proc/interrupts shows iavf interrupts
(associated with physical devices running the i40e driver) on other CPUs
than the expected affinity. For example, here are some iavf interrupts
on CPU 4 where I would not expect to see any interrupts given that "cat
/proc/irq/<NUM>/smp_affinity_list" reports "0-1,24-25" for all these
interrupts. (Sorry for the line wrapping.)
cat /proc/interrupts | grep -e CPU -e 941: -e 942: -e 943: -e 944: -e
945: -e 961: -e 962: -e 963: -e 964: -e 965:
CPU0 CPU1 CPU2 CPU3 CPU4 CPU5
941: 0 0 0 0 28490 0
IR-PCI-MSI-edge iavf-0000:b5:03.6:mbx
942: 0 0 0 0 333832 0
IR-PCI-MSI-edge iavf-net1-TxRx-0
943: 0 0 0 0 300842 0
IR-PCI-MSI-edge iavf-net1-TxRx-1
944: 0 0 0 0 333845 0
IR-PCI-MSI-edge iavf-net1-TxRx-2
945: 0 0 0 0 333822 0
IR-PCI-MSI-edge iavf-net1-TxRx-3
961: 0 0 0 0 28492 0
IR-PCI-MSI-edge iavf-0000:b5:02.7:mbx
962: 0 0 0 0 435608 0
IR-PCI-MSI-edge iavf-net1-TxRx-0
963: 0 0 0 0 394832 0
IR-PCI-MSI-edge iavf-net1-TxRx-1
964: 0 0 0 0 398414 0
IR-PCI-MSI-edge iavf-net1-TxRx-2
965: 0 0 0 0 192847 0
IR-PCI-MSI-edge iavf-net1-TxRx-3
There were IRQs coming in on the "iavf-0000:b5:02.7:mbx" interrupt at
roughly 1 per second without any traffic, while the interrupt rate on
the "iavf-net1-TxRx-<X>" seemed to be related to traffic.
Is this expected? It seems like the IRQ subsystem is not respecting the
configured SMP affinity for the interrupt in question. I've also seen
the same behaviour with igb interrupts.
Anyone have any ideas?
Thanks,
Chris
