libvirt users - Jun 2014 - libvirt on OpenStack

Hi,

I am running OpenStack Cluster and use libvirt + cgroup to limit vm’s
performance
https://wiki.openstack.org/InstanceResourceQuota

What I am confusing is..

1. After running a vm instance with some croup limit applied, I can’t find any
related cgroup settings.
2. Can I change limit value after instance is running? like change
disk_read_iops_sec from 10 to 20.

One of the xml file like below.

<domain type="kvm">
  <uuid>27f49e5c-8ee0-4a09-8269-5fa31acd2983</uuid>
  <name>instance-000000da</name>
  <memory>2097152</memory>
  <vcpu cpuset="1-12">1</vcpu>
  <sysinfo type="smbios">
    <system>
      <entry name="manufacturer">Red Hat Inc.</entry>
      <entry name="product">OpenStack Nova</entry>
      <entry name="version">2013.2.3-1.el6</entry>
      <entry
name="serial">9fa4736a-2b02-11e1-a8e4-5cf3fcb968b4</entry>
      <entry
name="uuid">27f49e5c-8ee0-4a09-8269-5fa31acd2983</entry>
    </system>
  </sysinfo>
  <os>
    <type>hvm</type>
    <boot dev="hd"/>
    <smbios mode="sysinfo"/>
  </os>
  <features>
    <acpi/>
    <apic/>
  </features>
  <clock offset="utc">
    <timer name="pit" tickpolicy="delay"/>
    <timer name="rtc" tickpolicy="catchup"/>
  </clock>
  <cpu mode="host-model" match="exact"/>
  <devices>
    <disk type="file" device="disk">
      <driver name="qemu" type="qcow2"
cache="none"/>
      <source
file="/data1/lib/nova/instances/27f49e5c-8ee0-4a09-8269-5fa31acd2983/disk"/>
      <target bus="virtio" dev="vda"/>
      <iotune>
        <read_bytes_sec>25600000</read_bytes_sec>
        <write_bytes_sec>40960000</write_bytes_sec>
      </iotune>
    </disk>
    <interface type="bridge">
      <mac address="fa:16:3e:49:04:ce"/>
      <model type="virtio"/>
      <source bridge="br-int"/>
      <target dev="tape30b3c05-12"/>
      <virtualport type="openvswitch">
        <parameters
interfaceid="e30b3c05-126c-45bd-ac31-e5eb5481a652"/>
      </virtualport>
    </interface>
    <serial type="file">
      <source
path="/data1/lib/nova/instances/27f49e5c-8ee0-4a09-8269-5fa31acd2983/console.log"/>
    </serial>
    <serial type="pty"/>
    <input type="tablet" bus="usb"/>
    <graphics type="vnc" autoport="yes"
keymap="en-us" listen="10.13.128.43"/>
  </devices>
</domain>

✉ --
朴元奎
kerwin

On 06/27/2014 05:48 PM, kerwin wrote:
> Hi,
>
> I am running OpenStack Cluster and use libvirt + cgroup to limit vm's 
> performance
> https://wiki.openstack.org/InstanceResourceQuota
>
> What I am confusing is..
>
> 1. After running a vm instance with some croup limit applied, I can't 
> find any related cgroup settings.
well, there are two kinds of iotune for vm instance storage.
1. cgroup way:
as http://libvirt.org/formatdomain.html#elementsBlockTuning described,
the <blkiotune> element should be configured under <domain>.

2. qemu way:
For some reason, qemu provides block iotune,
see http://libvirt.org/formatdomain.html#elementsDisks
This capability you used is implemented inside qemu.
> 2. Can I change limit value after instance is running? like change 
> disk_read_iops_sec from 10 to 20.
>
> One of the xml file like below.
>
> <domain type="kvm">
> <uuid>27f49e5c-8ee0-4a09-8269-5fa31acd2983</uuid>
>   <name>instance-000000da</name>
>   <memory>2097152</memory>
>   <vcpu cpuset="1-12">1</vcpu>
>   <sysinfo type="smbios">
>     <system>
>       <entry name="manufacturer">Red Hat Inc.</entry>
>       <entry name="product">OpenStack Nova</entry>
>       <entry name="version">2013.2.3-1.el6</entry>
>       <entry
name="serial">9fa4736a-2b02-11e1-a8e4-5cf3fcb968b4</entry>
>       <entry
name="uuid">27f49e5c-8ee0-4a09-8269-5fa31acd2983</entry>
>     </system>
>   </sysinfo>
>   <os>
>     <type>hvm</type>
>     <boot dev="hd"/>
>     <smbios mode="sysinfo"/>
>   </os>
>   <features>
>     <acpi/>
>     <apic/>
>   </features>
>   <clock offset="utc">
>     <timer name="pit" tickpolicy="delay"/>
>     <timer name="rtc" tickpolicy="catchup"/>
>   </clock>
>   <cpu mode="host-model" match="exact"/>
>   <devices>
>     <disk type="file" device="disk">
>       <driver name="qemu" type="qcow2"
cache="none"/>
>       <source 
>
file="/data1/lib/nova/instances/27f49e5c-8ee0-4a09-8269-5fa31acd2983/disk"/>
>       <target bus="virtio" dev="vda"/>
>       <iotune>
> <read_bytes_sec>25600000</read_bytes_sec>
> <write_bytes_sec>40960000</write_bytes_sec>
>       </iotune>
>     </disk>
>     <interface type="bridge">
>       <mac address="fa:16:3e:49:04:ce"/>
>       <model type="virtio"/>
>       <source bridge="br-int"/>
>       <target dev="tape30b3c05-12"/>
>       <virtualport type="openvswitch">
>         <parameters
interfaceid="e30b3c05-126c-45bd-ac31-e5eb5481a652"/>
>       </virtualport>
>     </interface>
>     <serial type="file">
>       <source 
>
path="/data1/lib/nova/instances/27f49e5c-8ee0-4a09-8269-5fa31acd2983/console.log"/>
>     </serial>
>     <serial type="pty"/>
>     <input type="tablet" bus="usb"/>
>     <graphics type="vnc" autoport="yes"
keymap="en-us"
> listen="10.13.128.43"/>
>   </devices>
> </domain>
>
> ? --
> ???
> kerwin
>
>
>
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