Ansible slowness due to a large number of network interface facts
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
kolla-ansible |
Fix Released
|
Medium
|
Rafael Weingartner |
Bug Description
This small patch speeds up kolla-ansible runs in production
environments with many network interfaces on the network and
compute nodes.
Before applying this patch, we tried the following tunnings:
* Increased the number of forks (great speedup depending of the size of
the deployment)
* Use `strategy = mitogen_linear` (cut processing time in half)
* Ansible caching (little speed up)
* SSH tunning (little speed up)
The biggest speedup (about 18x) was achieved with the ansible facts
filtering. We guess that the best option, for now, is this patch. In
the future, we could get in touch with the ansible community to enable
extend facts filtering like, eg. allow users to define multiple filters
for each subset.
We experimented with this patch, using the following command.
```
EXTRA_OPTS='--check --diff' kolla-ansible -i inventory genconfig -t ceilometer
```
Changed in kolla-ansible: | |
assignee: | nobody → Rafael Weingartner (rafaelweingartner) |
summary: |
- Fixes ansible facts slowness + Ansible slowness due to a large number of network interface facts |
Changed in kolla-ansible: | |
importance: | Undecided → Medium |
Changed in kolla-ansible: | |
status: | New → In Progress |
Reviewed: https:/ /review. opendev. org/c/openstack /kolla- ansible/ +/783392 /opendev. org/openstack/ kolla-ansible/ commit/ 15f2fdcd5dd9e63 b477c549c2af990 df8235ca90
Committed: https:/
Submitter: "Zuul (22348)"
Branch: master
commit 15f2fdcd5dd9e63 b477c549c2af990 df8235ca90
Author: Rafael Weingärtner <email address hidden>
Date: Fri Mar 26 14:19:39 2021 -0300
Make setup module arguments configurable
Ansible facts can have a large impact on the performance of the Ansible ansible_ setup_gather_ subset) and which facts are stored ansible_ setup_filter) . By default we do not change the default
control host. This patch introduces some control over which facts are
gathered (kolla_
(kolla_
values of these arguments to the setup module. The flexibility of these
arguments is limited, but they do provide enough for a large performance
improvement in a typical moderate to large OpenStack cloud.
In particular, the large complex dict fact for each interface has a setup_filter
large effect, and on an OpenStack controller or hypervisor there may be
many virtual interfaces. We can use the kolla_ansible_
variable to help:
This causes Ansible to collect but not store facts matching that
pattern, which includes the virtual interface facts. Currently we are
not referencing other facts matching the pattern within Kolla Ansible.
Note that including the 'ansible_' prefix causes meta facts module_setup
and gather_subset to be filtered, but this seems to be the only way to
get a good match on the interface facts. To work around this, we use
ansible_facts rather than module_setup to detect whether facts exist in
the cache.
The exact improvement will vary, but has been reported to be as large as
18x on systems with many virtual interfaces.
For reference, here are some other tunings tried:
* Increased the number of forks (great speedup depending of the size of
the deployment)
* Use `strategy = mitogen_linear` (cut processing time in half)
* Ansible caching (little speed up)
* SSH tunning (little speed up)
Co-Authored-By: Mark Goddard <email address hidden> 2f1dc65e1b10381 d2e26e88805
Closes-Bug: #1921538
Change-Id: Iae8ca4aae94589