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Is cgroup required to be enabled for kvm compute nodes?

asked 2015-04-03 10:44:26 -0500

AaronTSmith gravatar image

Sorry for the general question. Does cgroup functionality need to be enabled on kvm nodes in an IceHouse Openstack environment? Does Openstack function with cgroups disabled? If so, are there major drawbacks to having cgroups disabled?

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answered 2015-04-07 07:08:29 -0500

Charles Benon gravatar image

Hi Aaron,

For what I read/know, you shouldn't need the cgroups or quotas to run instances (but, they are useful as they give you a way to limit access to resources):

https://wiki.openstack.org/wiki/Insta...

Do you get any errors if you don't use them ?

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Thanks for the updated link. I had seen an earlier version.

We are seeing performance issues when cgroups are running and we see them disappear when cgroups is disabled on the compute node. We also see issues with time drift when cgroups are enabled. I believe the root cause is a bad Centos inst

AaronTSmith gravatar imageAaronTSmith ( 2015-04-07 08:34:04 -0500 )edit

Ok, what type of issues ? Do you have a chance to compare both of the environments or you use the same compute node ?

Charles Benon gravatar imageCharles Benon ( 2015-04-07 08:49:39 -0500 )edit

We are seeing horrible disk I/O performance with cgroups turned on. With cgroups on, we get local disk throughput of 10MB/s. With cgroups on, we get several hundred. We obviously have cgroups misconfigured. Checking our settings. Thanks.

AaronTSmith gravatar imageAaronTSmith ( 2015-04-07 12:36:15 -0500 )edit

Could you post the content of /etc/cgconfig.conf ?

Did you install or enable them, or, was it per default ?

What is the CentOS version ?

Charles Benon gravatar imageCharles Benon ( 2015-04-07 16:11:51 -0500 )edit

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Asked: 2015-04-03 10:44:26 -0500

Seen: 393 times

Last updated: Apr 07 '15