On 06/06/16 13:26 +0300, Дмитрий Глушенок wrote:
Hello Martin,
Thank you for your time. It is clear how to create partition and assign it to a
VM. But libvirt manipulates with contents of devices.list and I didn't find a
way to put my devices into devices.list and stop libvirt from removing them.
That is, by the way, pretty interesting. I have tried it right now and
when using custom partition, libvirt doesn't touch my devices.list.
It might make sense to file a libvirt bug.
Anyway, it looks like that the best solution will be using oVirt 4.0 where scsi
pass-through have been fixed.
Hoping so!
--
Dmitry Glushenok
Jet Infosystems
http://www.jet.msk.su <http://www.jet.msk.su/>+7-495-411-7601 (ext. 1237)
6 июня 2016 г., в 12:33, Martin Polednik <[email protected]> написал(а):
On 03/06/16 14:05 +0300, Дмитрий Глушенок wrote:
Thank you Martin!
Actually I tried the workaround hook, provided in [2], but then VDSM (oVirt
3.6.6) tries to interpret hostdev in XML as PCI device, which leads to:
::The vm start process failed
Traceback (most recent call last):
File "/usr/share/vdsm/virt/vm.py", line 703, in _startUnderlyingVm
self._run()
File "/usr/share/vdsm/virt/vm.py", line 1949, in _run
self._domDependentInit()
File "/usr/share/vdsm/virt/vm.py", line 1797, in _domDependentInit
self._getUnderlyingVmDevicesInfo()
File "/usr/share/vdsm/virt/vm.py", line 1738, in _getUnderlyingVmDevicesInfo
self._getUnderlyingHostDeviceInfo()
File "/usr/share/vdsm/virt/vm.py", line 4277, in _getUnderlyingHostDeviceInfo
**self._getUnderlyingDeviceAddress(source))
TypeError: pci_address_to_name() got an unexpected keyword argument 'target'
XML part was:
<hostdev managed="no" mode="subsystem" rawio="yes" type="scsi">
<source>
<adapter name="scsi_host2"/>
<address bus="0" target="1" unit="0"/>
</source>
</hostdev>
<hostdev managed="no" mode="subsystem" rawio="yes" type="scsi">
<source>
<adapter name="scsi_host2"/>
<address bus="0" target="2" unit="0"/>
</source>
</hostdev>
As of creating custom partition - by default machine.slice has "a *:* rwm" in
devices.list. But for every new VM libvirt removes *:* mask and fills the list with
actually needed devices (as I understand the process). For example:
c 136:* rw
c 1:3 rw
c 1:7 rw
c 1:5 rw
c 1:8 rw
c 1:9 rw
c 5:2 rw
c 10:232 rw
c 253:0 rw
c 10:228 rw
c 10:196 rw
What I'm looking for is a way to tell libvirt about my additional devices
without breaking oVirt.
The solution would be creating your own partition and somehow (e.g.
VDSM hook) appending
<resource>
<partition>/machine/custom</partition>
</resource>
to the libvirt's <domain> element. I'm not sure how feasible creating
your own partition is though. I've tried the process as follows:
$ cat ~/create-partition.sh
# sh ~/create-partition.sh
for i in blkio cpu,cpuacct cpuset devices freezer memory net_cls perf_event
do
mkdir /sys/fs/cgroup/$i/machine.slice/custom.partition
done
for i in cpuset.cpus cpuset.mems
do
cat /sys/fs/cgroup/cpuset/machine.slice/$i >
/sys/fs/cgroup/cpuset/machine.slice/custom.partition/$i
done
(creates /machine/custom partition).
Now, we can create vdsm before_vm_start hook that will set given partition
for the VM:
$ pwd /usr/libexec/vdsm/hooks/before_vm_start
$ cat 10_cgroups
#!/usr/bin/python
import hooking
def custom_partition(domxml):
resource = domxml.createElement('resource')
partition = domxml.createElement('partition')
partition_text = domxml.createTextNode('/machine/custom')
partition.appendChild(partition_text)
resource.appendChild(partition)
return resource
domxml = hooking.read_domxml()
domain = domxml.getElementsByTagName('domain')[0]
domain.appendChild(custom_partition(domxml))
hooking.write_domxml(domxml)
--
Dmitry Glushenok
Jet Infosystems
http://www.jet.msk.su
+7-495-411-7601 (ext. 1237)
3 июня 2016 г., в 12:24, Martin Polednik <[email protected]> написал(а):
On 03/06/16 11:48 +0300, Дмитрий Глушенок wrote:
Hello!
Is it possible to tell libvirt to add specific devices to qemu cgroup? By
somehow enumerating the devices in XML using a hook for example.
I'm passing scsi-generic disks (/dev/sgX) to VM using qemucmdline hook and it doesn't
work until I remove "devices" from cgroup_controllers in qemu.conf.
One way to achieve this is creating a hook to generate the scsi device
XML instead of modifying qemu cmdline directly. Libvirt assumes
ownership of all devices created in the XML and therefore adds them to
the machine cgroup.
Example of the XML taken from [1]:
<devices>
<hostdev mode='subsystem' type='scsi' sgio='filtered' rawio='yes'>
<source>
<adapter name='scsi_host0'/>
<address bus='0' target='0' unit='0'/>
</source>
<readonly/>
<address type='drive' controller='0' bus='0' target='0' unit='0'/>
</hostdev>
</devices>
There is slight issue with this approach outlined in [2].
If you want to keep the qemu approach, I think creating a custom
partition and moving devices there would be the cleanest approach. In
this case, [3] could help but I'm not entirely sure if that would
solve the issue.
[1] https://libvirt.org/formatdomain.html
[2] https://bugzilla.redhat.com/show_bug.cgi?id=1325485
[3] https://libvirt.org/cgroups.html
--
Dmitry Glushenok
Jet Infosystems
http://www.jet.msk.su
+7-495-411-7601 (ext. 1237)
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