On 06/21/2017 02:42 AM, Henning Schild wrote:
Am Tue, 20 Jun 2017 10:41:44 -0600
schrieb Chris Friesen <chris.frie...@windriver.com>:
Our goal is to reach a high packing density of realtime VMs. Our
pragmatic first choice was to run all non-vcpu-threads on a shared
set of pcpus where we also run best-effort VMs and host load.
Now the OpenStack guys are not too happy with that because that is
load outside the assigned resources, which leads to quota and
accounting problems.
If you wanted to go this route, you could just edit the
"vcpu_pin_set" entry in nova.conf on the compute nodes so that nova
doesn't actually know about all of the host vCPUs. Then you could
run host load and emulator threads on the pCPUs that nova doesn't
know about, and there will be no quota/accounting issues in nova.
Exactly that is the idea but OpenStack currently does not allow that.
No thread will ever end up on a core outside the vcpu_pin_set and
emulator/io-threads are controlled by OpenStack/libvirt.
Ah, right. This will isolate the host load from the guest load, but it will
leave the guest emulator work running on the same pCPUs as one or more vCPU threads.
Your emulator_pin_set idea is interesting...it might be worth proposing in nova.
Chris
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