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Some questions regarding the CPU

Dom Nik

Hi all,

I have some questions regarding the CPU settings and the behavior when running the XG as a KVM. It seems there is no discussion about these things yet, so I decided to create a thread.

1. When running the CPU with the type "host" or "kvm64" for the KVM I noticed that the CPU cache is set to 16MB in XG while my CPU has 2MB L3 cache only. (cat /proc/cpuinfo)

2. I found a setting in the CLI called port-affinity. With the default setting the CPU core 1 is selected for all network interfaces. The IPS seems to prefer core 1 as well (with 2 IPS threads configured as default). What would the best setup here? Which command should be used to change the affinity? (bind-with, start-with, cpu)

3. Are there any options to permanently setup the multiqueue feature with virtio drivers in XG? According to the docu (https://pve.proxmox.com/wiki/Qemu/KVM_Virtual_Machines)  you need to activate multiqueue in the VM with the following command for each interface: ethtool -L <interface> combined X - However this will be reset after a reboot.

Thanks and best regards

Dom Nik



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    Old thread, same questions. :-)

     

    Finally I got some answers for the points 1 and 3:

    1. The cache settings seem to be hardcoded in KVM, so this is as it is.

    3. The multiqueue feature is now working out of the box. I don't know which XG version introduced it, but with v18 MR1, the "combined" setting is applied automatically after a reboot.

     

    However I'm still interested in the point of port-affinity. Is there any information and best practices available for this? Right now with a 4-core machine, the default port-affinity is on cores 3 and 4 only.

    Best Regards

    Dom