== areas of performance ==

Every layer of the stack as described in https://tannerjc.net/wiki/index.php?title=Ansible_Hangs_Filament#Tools_By_Layer is potentially a source of performance issues.

== strategies ==

=== getting started ===

=== many tasks ===

=== many hosts ===

=== many groups ===

=== many vars ===

== metrics ==
=== duration ===

[https://en.wikipedia.org/wiki/Duration Duration] is a measurement of time. There are multiple facets of "duration" when observing Ansible.

* total duration of a playbook
* total duration of a task
* total duration of a host within a task
* total duration of an ssh call for a host within a task
* total duration of wating for a sudo password prompt
* total duration of executing python on the remote host
* total duration of processing the results for a host/worker

=== cpu utilization ===

Aka [https://en.wikipedia.org/wiki/CPU_time CPU time]. Many tools exist to measure cpu time / utilization and it's important to understand the various metrics each provides.

https://access.redhat.com/solutions/1160343

An important metric for basic ansible cpu utilization is the "b" (aka "blocked) column from vmstat. 

https://linux.die.net/man/8/vmstat <br>
http://www.dba-oracle.com/t_linux_oracle_vmstat.htm <br>
https://access.redhat.com/solutions/792683 <br>

Multiple factors could cause the number of blocked processes to accumulate.

* not enough cpu cores
** setting ansible's fork count too high
* not enough memory
** too many hosts returning too much data for the controller to handle
* not enough disk IOPs

=== memory utilization === 
=== disk utilization ===
=== network utilization ===

== tools ==
https://docs.ansible.com/ansible/devel/plugins/callback/cgroup_memory_recap.html <br>
https://github.com/jctanner/ansible-tools/blob/master/ansible_debug_logparser <br>

https://github.com/ansible/qa-scale-lab <br>
https://github.com/jctanner/ansible-tools/tree/master/vagrant/ansible_test_inventory <br>

== labs ==

https://github.com/jctanner/ansible-tools/tree/master/playbooks/slowhost

== training ==

https://www.redhat.com/en/services/training/rh442-red-hat-enterprise-performance-tuning <br>
https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/performance_tuning_guide/chap-red_hat_enterprise_linux-performance_tuning_guide-performance_monitoring_tools


== additional reading ==

https://gist.github.com/sivel/ef405e70f699ce29c49cfdf6104a0492