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>

✉ --

朴元奎

kerwin
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