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[Eric Miller <1785511@xxxxxxxxxxxxxxxxxx>]

Public bug reported:

Environment is Kolla-Ansible 6.1.0 deployed (Queens) on physical
hardware (Xeon Gold 6154 compute nodes).

Deploying an image with the following flavor (for a "nano" sized
instance) does not throttle the single vCPU to 1/10th of a physical
thread or core.  The VM has full performance of a single physical
thread.

openstack flavor create --property cpu_quota=10000 --property
cpu_period=100000 --vcpus=1 --ram 512 --disk 0 --public "t5.test"


virsh on the compute node lists the following scheduling info:

virsh # edit 25
Domain instance-0000001e XML configuration not changed.

virsh # schedinfo 25
Scheduler      : posix
cpu_shares     : 1024
vcpu_period    : 100000
vcpu_quota     : -1
emulator_period: 100000
emulator_quota : -1
global_period  : 100000
global_quota   : -1
iothread_period: 100000
iothread_quota : -1

Manually forcing the vcpu_quota to 10000 (instead of 100000), results in
the VM being throttled to 10% of a physical thread or core:

schedinfo 25 --set vcpu_quota=10000


NOTE that Libvirt uses vcpu_quota (with a "v") whereas the openstack flavor properties use cpu_quota.  So, I tried to use vcpu_quota and vcpu_period in the OpenStack flavor properties, but this did not affect Libvirt's XML config file.

Am I missing something or is this a bug?

Thanks!

Eric

** Affects: nova
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1785511

Title:
  cpu_quota does not throttle cpu usage

Status in OpenStack Compute (nova):
  New

Bug description:
  Environment is Kolla-Ansible 6.1.0 deployed (Queens) on physical
  hardware (Xeon Gold 6154 compute nodes).

  Deploying an image with the following flavor (for a "nano" sized
  instance) does not throttle the single vCPU to 1/10th of a physical
  thread or core.  The VM has full performance of a single physical
  thread.

  openstack flavor create --property cpu_quota=10000 --property
  cpu_period=100000 --vcpus=1 --ram 512 --disk 0 --public "t5.test"

  
  virsh on the compute node lists the following scheduling info:

  virsh # edit 25
  Domain instance-0000001e XML configuration not changed.

  virsh # schedinfo 25
  Scheduler      : posix
  cpu_shares     : 1024
  vcpu_period    : 100000
  vcpu_quota     : -1
  emulator_period: 100000
  emulator_quota : -1
  global_period  : 100000
  global_quota   : -1
  iothread_period: 100000
  iothread_quota : -1

  Manually forcing the vcpu_quota to 10000 (instead of 100000), results
  in the VM being throttled to 10% of a physical thread or core:

  schedinfo 25 --set vcpu_quota=10000

  
  NOTE that Libvirt uses vcpu_quota (with a "v") whereas the openstack flavor properties use cpu_quota.  So, I tried to use vcpu_quota and vcpu_period in the OpenStack flavor properties, but this did not affect Libvirt's XML config file.

  Am I missing something or is this a bug?

  Thanks!

  Eric

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