On Tue, Feb 23, 2021 at 4:10 PM Lavi.Buchnik--- via Users <users@ovirt.org> wrote:

Hi,

We have a strange thing, which not clear to us. When provisioning a new VM via REST API, if the number of vCPU for that VM is more than 16, I'm getting this error:

Fault reason is "Operation Failed". Fault detail is "[Cannot add VM. Maximum number of threads per cpu exceeded]". HTTP response code is 409.

Our version is: Version 4.3.6.6-1.0.9.el7

Note that manual provisioning from the UI do not produce any error when using vCPU > 16. It seems like the issue is related to this setting (from the engine):

[root@olvmengine01 ~]# engine-config -g MaxNumOfThreadsPerCpu MaxNumOfThreadsPerCpu: 8 version: 4.1 MaxNumOfThreadsPerCpu: 8 version: 4.2 MaxNumOfThreadsPerCpu: 8 version: 4.3 [root@olvmengine01 ~]#

But when trying to set it to another number, I'm always get this error, for example:

[root@olvmengine01 ~]# engine-config -s MaxNumOfThreadsPerCpu=10 Please select a version: 1. 4.1 2. 4.2 3. 4.3 3 Cannot set value 10 to key MaxNumOfThreadsPerCpu.

Questions: 1. Can you please explain why we getting this error: "Cannot add VM. Maximum number of threads per cpu exceeded"?

You've specified a value for threads-per-core that exceeds the MaxNumOfThreadsPerCpu limit. 2. Is it related to engine-config -g MaxNumOfThreadsPerCpu?

Yes

3. Why it is working manually via the UI?

The UI sets the CPU topology for you when you specify the number of vCPUs (for 16, it produces #sockets = 16, #cores=1, #threads=1).

4. if its related to engine-config, why we can't set it to another number?

You can change the values that engine-config accepts for MaxNumOfThreadsPerCpu by changing MaxNumOfThreadsPerCpu.validValues in /etc/ovirt-engine/engine-config/engine-config.properties but I think it would be better to specify a better CPU topology in the request..

Thanks in advance, Lavi _______________________________________________ Users mailing list -- users@ovirt.org To unsubscribe send an email to users-leave@ovirt.org Privacy Statement: https://www.ovirt.org/privacy-policy.html oVirt Code of Conduct: https://www.ovirt.org/community/about/community-guidelines/ List Archives: https://lists.ovirt.org/archives/list/users@ovirt.org/message/CRKRVCWPUIN6HG...