On Fri, 2019-04-12 at 10:53 +0200, Bastian Blank wrote: > Moin > > It turns out we got again problems with irqbalance. > > It was added as recommends of the main image in 3.16, as it was reported > that older kernels move all interrupts to CPU 0 without help.[1] > > In the meantime the kernel can do balancing on it's own. In 4.9, I've > seen it working with aacraid, each queue gets hard pinned to it's own > CPU from 0 to $NRCPUS. In 4.19 I've seen the same working properly with > virtio-net. > > With 4.19, even on real hardware, where interrupts have an affinity for > all cpus, each interrupt is actually delivered to different cpu. > > Random example for this, it even selects only one thread of each core: > > > 26: 0 0 0 0 92 0 0 0 IR-PCI-MSI 3670017-edge eno1-TxRx-0 > > 27: 0 0 0 0 0 167 0 0 IR-PCI-MSI 3670018-edge eno1-TxRx-1 > > 28: 0 0 0 0 0 0 467 0 IR-PCI-MSI 3670019-edge eno1-TxRx-2 > > 29: 0 0 0 0 0 0 0 454 IR-PCI-MSI 3670020-edge eno1-TxRx-3 > > Now irqbalance comes to re-do the existing pinning, and the result is not > longer correct but $RANDOM for the hard queue-to-cpu case of virtio. Then let's drop the recommendation. Ben. > At least Google considers the work irqbalance does to "correct" the existing > balancing a large problem. > > I'm not sure how to go forward. I have a workaround pending for our > cloud images to hard exclude the installation of irqbalance.[2] > > Regards, > Bastian > > [1]: https://bugs.debian.org/577788 > [2]: https://salsa.debian.org/cloud-team/debian-cloud-images/merge_requests/81 -- Ben Hutchings Hoare's Law of Large Problems: Inside every large problem is a small problem struggling to get out.
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