Lower overcommit ratios

[Ian Cordasco]

Opened by BjoernT on 2014-11-04 20:18:43+00:00 at https://github.com/rcbops/ansible-lxc-rpc/issues/470

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See nova_cpu_allocation_ratio at inventory/group_vars/nova_all.yml and lower that from 10.0 to 2.0
2.0 seems to be the most requested ratio.

Tags: Backport Potential, doc, enhancement, in progress, needs review, prio:2

====================== COMMENTS ============================

Comment created by BjoernT on 2014-11-11 16:29:38+00:00

Additionally set RAM overcommit ratio to 1.0

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Comment created by claco on 2014-11-11 18:46:06+00:00

Sounds like these types of settings should be templated, so we can tweak them per compute/customer/installation.

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Comment created by BjoernT on 2014-11-11 21:46:11+00:00

Yes templeting is ok, as long as we don't use such high default values

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Comment created by mattt416 on 2014-11-12 10:25:37+00:00

Would it be prudent to get someone else in support to :+1: this request?

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Comment created by mancdaz on 2014-11-12 11:11:23+00:00

@BjoernT @mattt416 @claco These are [already templated](https://github.com/rcbops/ansible-lxc-rpc/blob/master/rpc_deployment/inventory/group_vars/nova_all.yml#L71-L75), and the default cpu_allocation_ratio was already dropped to 5.0 in master [here](https://github.com/rcbops/ansible-lxc-rpc/commit/f2e5946e2acc42acc0ecb42604a2b0be8f468ec0)

We can either cherry pick that commit into the 9.x series and include in the next tag release, or change the default to something else in both current master and 9.x series. As @mattt416 says though, perhaps a support consensus is required before we change those defaults.

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Comment created by BjoernT on 2014-11-12 14:45:22+00:00

Added @cfarquhar if he shares the same opinion as me

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Comment created by b3rnard0 on 2014-11-13 17:41:26+00:00

@klevenstein Has doc impact.

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Comment created by cfarquhar on 2014-11-13 17:43:16+00:00

Per discussion, this is templated in 9.0.1. We should use 2:1 for default CPU overcommit and make sure the proper way to override is documented.

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Comment created by mancdaz on 2014-11-14 10:23:56+00:00

@cfarquhar actually whilst this is a group var that is changeable, it needs to be moved into the user_variables file so that updates don't clobber the manual change to the group_var (ie I was somewhat mistaken above)

I'll get the default cpu overcommit changed to 2:1 if that is the consensus, and the memory overcommit default set to 1:1, and move both of those into the user_variables file for easy overriding.

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Comment created by klevenstein on 2014-11-17 19:43:59+00:00

We don't currently have overcommit ratios documented, but can add. At what stage of the process (foundation, infra, or OpenStack playbooks) does this need to be specified?

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Comment created by BjoernT on 2014-11-17 21:11:06+00:00

Overcommit ratios can be configured along rpc_user_config configuration since it's primarily a first time configuration. Technically it belongs to the openstack. I can't think of having seen a openstack specific configuration, so we either append it after the rpc_user_config or open a new paragraph for this, just openstack related configuration. I can imagine that wouldn't be the only parameters we have to change openstack related

[Kevin Carter (kevin-carter)]

related review https://review.openstack.org/#/c/139250/