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We welcome your contributions to the Performance Co-Pilot project!


Our preferred method of exchanging code, documentation, tests and new ideas is via git. To participate, create a cloned git tree using a public git hosting service (e.g. github) and send mail to the list - - with a description of the code and its location.

Patches are fine too - send 'em through to the list at any time - even just ideas, pseudo-code, etc - we've found it is often a good idea to seek early feedback, particularly when modelling the metrics you'll be exporting from any new PMDAs you might be writing.


If you have discovered a vulnerability in the PCP code, please do not hesitate to contact the PCP maintainers immediately.

You can choose to do this either privately or publicly - however, if you report to the maintainers privately at first we will endeavour to respond within 24 hours with an initial assessment of the problem and a timeframe for resolution and next release with the fix(es).

The maintainers can be contacted privately via


PCP development has a long tradition of focussing on automated testing.

New tests should be added to the testsuite with new code. This is not a hard requirement when sending out patches or git commits, however, particularly as a new contributor. Someone else will work with you to introduce an appropriate level of testing to exercise your fix or new code, and that will end up being committed along with your new changes.

For the more practiced, regular PCP committers: testing is assumed to have been done for all commits - both regression testing, using all of the existing tests, and addition of new tests to exercise the commits. A guide to using the automated quality assurance test suite exists in the qa/README file.

For the very practiced, life members of the team: please help out in terms of getting new contributors moving with their patches - writing tests with them, giving feedback, and merging their code quickly. We aim to have new PMDA or monitoring tool contributions included in the release immediately following the first arrival of code. Also ensure attribution of other contributors code is handled correctly using the git-commit --author option.

Above all, have fun!

Coding Conventions

Add permanent diagnostics to any code of middling-to-high complexity. The convention is to test the options in the pmDebugOptions struct (from libpcp) which is supported by every tool via the -D/--debug option - see pmdbg(1) for details, and see also the many examples of its use in existing code.

Use the same coding style used in the code surrounding your changes.

All the existing code is GPL'd, so feel free to borrow and adapt code that is similar to the function you want to implement. This maximizes your chance of absorbing the "style" and "conventions" and producing code that others will be able to easily read, understand and refine.

QA (Quality Assurance) Practicalities

Refer to the qa/README file for details on using the testsuite locally. When writing new tests, bear in mind that other people will be running those tests alot. An ideal test is one that: small - several small tests trump one big test (allowing someone else debugging a test failure to quickly get their head around what the test does)

...runs in as short an amount of time as possible (allowing someone debugging a failure to iterate quickly through any ideas they have while working on the fix)

...uses the same style as all the other tests in the "qa" directory (other people will be debugging tests you write and you may need to debug other peoples tests as well - sticking to the same script style and conventions is universally helpful)

...uses filtering intelligently ... because tests pass or fail based on textual comparison of observed and expected output, it is critical to filter out the fluff (remove it or make it determinisitic) and retain the essence of what the test is exercising. See common.filter for some useful filtering functions, and watch out for things like: o dates and times (unless using archives) o use -z when using archives so the results are not dependent on the timezone where the test is run o the pid of the running test, especially when part of $tmp that is used extensively o collating sequences and locale ... take explicit control if in doubt portable, testing as many platforms as possible, for example: o use pmdasample rather than a pmda metric; o use archives for exercising exact behaviour of monitoring tools; o watch out for differences in output between system utilities; o before running, test for situations where it cannot run - such as unsupported platforms/configurations - use _notrun() here.