Imbalanced IRQs on virtio devices

Asked Dec 10 '18 at 13:58

Active Dec 10 '18 at 13:58

Viewed 672 times

I noticed in the top on my linux server that one cpu had far more number of software interrupts than all other 7 cores. Digging further, I noticed that this core is pinned to a particular irq which happens to be a virtio device. Infact each core has an affinity toward a particular virtio device

virtio0-config
virtio0-control
virtio0-event
virtio0-request
virtio2-config
virtio2-input.0
virtio2-output.0
virtio3-config
virtio3-input.0
virtio3-output.0
virtio4-config
virtio4-input.0
virtio4-output.0

In this list, virtio4-input.0 has in particular very high number of interrupts and I am not able to figure out what is special about this particular device. any clues will be very helpful.. The machine in question is a nutanix VM running on a linux host.

asked Dec 10 '18 at 13:58

hobgoblin

A lot of data is being sent over the network to that VM? That's the usual cause. – Michael Hampton Dec 10 '18 at 14:07
yeah. I was trying to find out what device does the virtio4 maps to. I was able to find that through readlink and the virtio device maps to eth2 interface of my machine. what I am curious now is that why did the kernel chose to use just one core for all the interrupts coming on that network interface.. – hobgoblin Dec 10 '18 at 16:04
Did someone stop the irqbalance daemon? – Michael Hampton Dec 10 '18 at 16:31
Nopes. Its still running. – hobgoblin Dec 11 '18 at 07:35

Imbalanced IRQs on virtio devices

0 Answers0