Open Stack

Hi Massimo,

We are using Ubuntu for our environments and we experienced the same issue during upgrade from Yoga/Focal to Yoga/Jammy. On Yoga/Focal cgroups_v1 were used, and cpu_shares parameter value was cpu count * 1024. From Jammy cgroups_v2 have been implemented, and cpu_shares value has been set by default to 100. It has hard limit of 10000, so flavors with more than 9vCPUs won't fit. If you need to fix this issue without stopping VMs, you can set cpu_shares with libvirt command: virsh schedinfo $domain --live cpu_shares=100
for more details about virsh schedinfo visit: https://libvirt.org/manpages/virsh.html#schedinfo 

BR,
Franciszek

> On 5 Oct 2023, at 21:17, smooney at redhat.com wrote:
> 
> On Thu, 2023-10-05 at 16:53 +0200, Massimo Sgaravatto wrote:
>> Dear all
>> 
>> We have recently updated openstack nova on some AlmaLinux9 compute nodes
>> running Yoga from 1:25.2.0 to 1.25.2.1. After this operation some VMs don't
>> start anymore. In the log it is reported:
>> 
>> libvirt.libvirtError: invalid argument: shares \'57344\' must be in range
>> [1, 10000]\n'}
>> 
>> libvirt version is 9.0.0-10.3
>> 
>> 
>> A quick google search suggests that it is something related to cgroups and
>> it is fixed in libvirt >= 9.1 (which is not yet in the almalinux9 repos).
>> Did I get it right ?
> not quite
> 
> it is reated to cgroups but the cause is that in cgroups_v1 the maxvlaue of shares
> i.e. cpu_shares changed form make int to 10000 in cgroups_v2
> so the issue is teh vm requested a cpu share value of 57344 which is not vlaid on an OS
> that is useing cgroups_v2 libvirt will not clamp the value nor will nova.
> you have to change the volue in your flavor and resize the vm.
> 
>> 
>> 
>> 
>> Thanks, Massimo
> 
> 

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