Re: Proposal for a regular upstream performance testing

[Stefan Hajnoczi <stefanha@redhat.com>]

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On Mon, Mar 21, 2022 at 09:46:12AM +0100, Lukáš Doktor wrote:
> Dear qemu developers,
> 
> you might remember the "replied to" email from a bit over year ago to raise a discussion about a qemu performance regression CI. On KVM forum I presented https://www.youtube.com/watch?v=Cbm3o4ACE3Y&list=PLbzoR-pLrL6q4ZzA4VRpy42Ua4-D2xHUR&index=9 some details about my testing pipeline. I think it's stable enough to become part of the official CI so people can consume, rely on it and hopefully even suggest configuration changes.
> 
> The CI consists of:
> 
> 1. Jenkins pipeline(s) - internal, not available to developers, running daily builds of the latest available commit
> 2. Publicly available anonymized results: https://ldoktor.github.io/tmp/RedHat-Perf-worker1/

This link is 404.

> 3. (optional) a manual gitlab pulling job which triggered by the Jenkins pipeline when that particular commit is checked
> 
> The (1) is described here: https://run-perf.readthedocs.io/en/latest/jenkins.html and can be replicated on other premises and the individual jobs can be executed directly https://run-perf.readthedocs.io on any linux box using Fedora guests (via pip or container https://run-perf.readthedocs.io/en/latest/container.html ).
> 
> As for the (3) I made a testing pipeline available here: https://gitlab.com/ldoktor/qemu/-/pipelines with one always-passing test and one allow-to-fail actual testing job. If you think such integration would be useful, I can add it as another job to the official qemu repo. Note the integration is a bit hacky as, due to resources, we can not test all commits but rather test on daily basis, which is not officially supported by gitlab.
> 
> Note the aim of this project is to ensure some very basic system-level workflow performance stays the same or that the differences are described and ideally pinned to individual commits. It should not replace thorough release testing or low-level performance tests.

If I understand correctly the GitLab CI integration you described
follows the "push" model where Jenkins (running on your own machine)
triggers a manual job in GitLab CI simply to indicate the status of the
nightly performance regression test?

What process should QEMU follow to handle performance regressions
identified by your job? In other words, which stakeholders need to
triage, notify, debug, etc when a regression is identified?

My guess is:
- Someone (you or the qemu.git committer) need to watch the job status and triage failures.
- That person then notifies likely authors of suspected commits so they can investigate.
- The authors need a way to reproduce the issue - either locally or by pushing commits to GitLab and waiting for test results.
- Fixes will be merged as additional qemu.git commits since commit history cannot be rewritten.
- If necessary a git-revert(1) commit can be merged to temporarily undo a commit that caused issues.

Who will watch the job status and triage failures?

Stefan

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