The VM Support to set Blkiotune

[matthewei]

Is your feature request related to a problem? Please describe:
Sometimes, we need to set the io performance of the disk.
such as read_bytes_sec, write_bytes_sec,read_iops_sec,write_iops_sec,total_bytes_sec,total_bytes_sec_max,total_bytes_sec_max_length,total_iops_sec,omitempty,total_iops_sec_max,total_iops_sec_max_length

Describe the solution you'd like:
I want to set iotune through vm's CRD. Please have a look the flowing phase.

matthew@ubuntu:~|⇒  kubectl explain vm.spec.template.spec.domain.devices.disks --recursive
KIND:     VirtualMachine
VERSION:  kubevirt.io/v1

RESOURCE: disks <[]Object>

DESCRIPTION:
     Disks describes disks, cdroms and luns which are connected to the vmi.

FIELDS:
   blockSize    <Object>
      custom    <Object>
         logical        <integer>
         physical       <integer>
      matchVolume       <Object>
         enabled        <boolean>
   bootOrder    <integer>
   cache        <string>
   cdrom        <Object>
      bus       <string>
      readonly  <boolean>
      tray      <string>
   dedicatedIOThread    <boolean>
   disk <Object>
      bus       <string>
      pciAddress        <string>
      readonly  <boolean>
   io   <string>
   iotune       <Object>
      read_bytes_sec    <integer>
      read_iops_sec     <integer>
      total_bytes_sec   <integer>
      total_bytes_sec_max       <integer>
      total_bytes_sec_max_length        <integer>
      total_iops_sec    <integer>
      total_iops_sec_max        <integer>
      total_iops_sec_max_length <integer>
      write_bytes_sec   <integer>
      write_iops_sec    <integer>
   lun  <Object>
      bus       <string>
      readonly  <boolean>
   name <string>
   serial       <string>
   shareable    <boolean>
   tag  <string>

Describe alternatives you've considered:
Please see the description of the previous stage.

Additional context:
Add any other context or screenshots about the feature request here.

[alicefr]

@matthewei we don't expose those values in the API, if you want tune those fields, you should use a sidecar.

[matthewei]

@alicefr Could you tell me the reason why it can't be exposed from the API? if we expose thoes values in the API and we can set this rules online. But I think you can't realize it if you use sidecar.

[matthewei]

The openstack has providerd this interface. Why don't we provide it?

[alicefr]

@matthewei this has been asked multiple times in the past, if you search, you will find multiple issues about this.
The main reason is that this expose too specific fields related to storage. Additionally, there is an ongoing KEP in Kubernetes that would allow to set the blockio tune parameters in the container. Once, this is merged and implemented, you could define a proper QoS class.

[matthewei]

okay, but the KEP support to set Blkiotune online?

[alicefr]

@matthewei yes, sorry I thought I had put the link, here it is: kubernetes/enhancements#3004

[matthewei]

Many Thanks @alicefr ，I still think that setting it directly through CRD is the best, we can specify the relevant settings explicitly, and it does not conflict with KEP. As an operator of DC, I only care about the creation parameters of the virtual machine