[openstack-dev] [nova] Extra feature of vCPU allocation on demands

[倪蔚辰]

Hi, all

I would like to propose a blueprint (not proposed yet), which is related to
openstack nova. I hope to have some comments by explaining my idea through
this e-mail. Please contact me if anyone has any comment.



Background

Under current OpenStack, vCPUs assigned to each VM can be configured as
dedicated or shared. In some scenarios, such as deploying Radio Access
Network VNF, the VM is required to have dedicated vCPUs to insure the
performance. However, in that case, each VM has a vCPU to do Guest OS
housekeeping. Usually, this vCPU is not a high performance required vCPU and
do not take high percentage of dedicated vCPU utilization. There is some
vCPU resources waste.



Proposed feature

I hope to add an extra feature to flavor extra specs. It refers to how many
dedicated vCPUs and how many shared vCPUs are needed for the VM. When VM
requires vCPU, OpenStack allocates vCPUs on demands. In the background
scenario, this idea can save many dedicated vCPUs which take Guest OS
housekeeping. And the scenario stated above is only one use case for the
feature. This feature potentially allows user to have more flexible VM
design to save CPU resource.



Thanks.



Weichen

e-mail: ***@chinamobile.com

[Jay Pipes]

Post by 倪蔚辰
Hi, all
I would like to propose a blueprint (not proposed yet), which is related
to openstack nova. I hope to have some comments by explaining my idea
through this e-mail. Please contact me if anyone has any comment.
Background
Under current OpenStack, vCPUs assigned to each VM can be configured as
dedicated or shared. In some scenarios, such as deploying Radio Access
Network VNF, the VM is required to have dedicated vCPUs to insure the
performance. However, in that case, each VM has a vCPU to do Guest OS
housekeeping. Usually, this vCPU is not a high performance required vCPU
and do not take high percentage of dedicated vCPU utilization. There is
some vCPU resources waste.
Proposed feature
I hope to add an extra feature to flavor extra specs. It refers to how
many dedicated vCPUs and how many shared vCPUs are needed for the VM.
When VM requires vCPU, OpenStack allocates vCPUs on demands. In the
background scenario, this idea can save many dedicated vCPUs which take
Guest OS housekeeping. And the scenario stated above is only one use
case for the feature. This feature potentially allows user to have more
flexible VM design to save CPU resource.

Please see here:

https://review.openstack.org/#/c/555081/

Best,
-jay

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[Eric Fried]

I will be interested to watch this develop. In PowerVM we already have
shared vs. dedicated processors [1] along with concepts like capped vs.
uncapped, min/max proc units, weights, etc. But obviously it's all
heavily customized to be PowerVM-specific. If these concepts made their
way into mainstream Nova, we could hopefully adapt to use them and
remove some tech debt.

[1]
https://github.com/openstack/nova/blob/master/nova/virt/powervm/vm.py#L372-L401

Post by 倪蔚辰
Hi, all
I would like to propose a blueprint (not proposed yet), which is related
to openstack nova. I hope to have some comments by explaining my idea
through this e-mail. Please contact me if anyone has any comment.
 
Background
Under current OpenStack, vCPUs assigned to each VM can be configured as
dedicated or shared. In some scenarios, such as deploying Radio Access
Network VNF, the VM is required to have dedicated vCPUs to insure the
performance. However, in that case, each VM has a vCPU to do Guest OS
housekeeping. Usually, this vCPU is not a high performance required vCPU
and do not take high percentage of dedicated vCPU utilization. There is
some vCPU resources waste.
 
Proposed feature
I hope to add an extra feature to flavor extra specs. It refers to how
many dedicated vCPUs and how many shared vCPUs are needed for the VM.
When VM requires vCPU, OpenStack allocates vCPUs on demands. In the
background scenario, this idea can save many dedicated vCPUs which take
Guest OS housekeeping. And the scenario stated above is only one use
case for the feature. This feature potentially allows user to have more
flexible VM design to save CPU resource.
 
Thanks.
 
Weichen
 
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