[mmarchini]

Ansible role to install Linux perf on Ubuntu by cloning the Linux source
code and building tools/perf to avoid Kernel mismatch errors.

I wasn't sure which playbook should call this role, so I'm submitting only
the role for now.

Tested on Ubuntu 16.04 from DigitalOcean.

Ref: #1274

[LucaLanziani]

Nice work, just a couple of comments in the PR and a couple of questions for the team to understand how to write those roles in the future (@mmarchini sorry if I'm using your code as example):

1. should we write the roles assuming they are running as privileged user? (eg. setting the become: true from the outside)
2. should we check for presence of perf at the start or should we just run the role every time? Assuming that the run is idempotent (like this seems to be)

[mmarchini]

Thanks for the suggestions! I updated the PR with them.

should we write the roles assuming they are running as privileged user?

I think so, at least looking at ansible.cfg and inventory.yml this seems to be true for most machines.

should we check for presence of perf at the start or should we just run the role every time?

The role will check if perf exists in /usr/local/bin/perf (i.e., if perf was installed by this role).

Which machine(s) should this be running on?

At least Ubuntu 16.04 machines used by stress-single-test. We might want to install perf on other machines later.

[mhdawson]

@jBarz since you did a bunch of ansible work for PPC/s390 could you take a look as well.

[maclover7]

should we write the roles assuming they are running as privileged user? (eg. setting the become: true from the outside)

Yes

should we check for presence of perf at the start or should we just run the role every time? Assuming that the run is idempotent (like this seems to be)

To be honest, probably best to always run the code. That's essentially what the rest of the roles do

[mmarchini]

@maclover7 @LucaLanziani done!

[maclover7]

Landed in a5d5962