KVM Host with 88 physical cores uses only 14 on 64 core Guest

Question

I do have a server with 2 CPUs (22 Cores each plus HT). I created a KVM Guest with 64 allocated cores. When I run a compilation task the virtual machine shows all 64 cores at 100% (at moderate Disk I/O and memory usage) but on the physical machine the guest only uses 14 cores at 100% instead of all the 88 cores randomly (or 64 dedicated cores at 100%). Even if I spawn more compilation tasks this doesn't change. Is there any parameter or setting I have to change to actually use all the computing power that is available?

I used an XML-Dump in virsh because it was a migration from an older server and changed configuration to match the new server in virt-manager. — HibikiTaisuna, Feb 17 '17 at 09:17
All cores except of the 14 show 0.0000s. But I could find at least one error. There was a vCPU pinning in the XML which doesn't appear in virt-manager -.- I removed it via `for i in {0..63}; do sudo virsh vcpupin $kvmdomain $i r --config; done` and restarted the guest. Unfortunately it still uses only the 14 cores. I will reboot the host to see if it still happens. — HibikiTaisuna, Feb 17 '17 at 10:10

score 12 · Accepted Answer · answered Feb 17 '17 at 11:35

12

There was a vCPU pinning in the XML which doesn't appear in virt-manager -.- I removed it via

for i in {0..63}; do sudo virsh vcpupin $kvmdomain $i r --config; done

and removed the line in the XML-file via

sudo virsh edit <domain>

After that I restarted the guest.

answered Feb 17 '17 at 11:35

HibikiTaisuna

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And now it works, yes? – Lenniey Feb 17 '17 at 12:20
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Until the comment by @Lenniey has been handled, this is not an answer to the question. – pipe Feb 17 '17 at 13:42
@Lenniey yes, now it works as intended – HibikiTaisuna Feb 22 '17 at 15:00

KVM Host with 88 physical cores uses only 14 on 64 core Guest

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