1. 21 Dec, 2018 1 commit
  2. 12 Nov, 2018 1 commit
  3. 07 Nov, 2018 1 commit
    • davide's avatar
      testsuite: Save performance metrics in git notes. · 932cd41d
      davide authored
      This patch makes the following improvement:
        - Automatically records test metrics (per test environment) so that
          the programmer need not supply nor update expected values in *.T
          - On expected metric changes, the programmer need only indicate the
            direction of change in the git commit message.
        - Provides a simple python tool "perf_notes.py" to compare metrics
          over time.
        - Using just the previous commit allows performance to drift with each
          - Currently we allow drift as we have a preference for minimizing
            false positives.
          - Some possible alternatives include:
            - Use metrics from a fixed commit per test: the last commit that
              allowed a change in performance (else the oldest metric)
            - Or use some sort of aggregate since the last commit that allowed
              a change in performance (else all available metrics)
            - These alternatives may result in a performance issue (with the
              test driver) having to heavily search git commits/notes.
        - Run locally, performance tests will trivially pass unless the tests
          were run locally on the previous commit. This is often not the case
          e.g.  after pulling recent changes.
      Previously, *.T files contain statements such as:
      stats_num_field('peak_megabytes_allocated', (2, 1))
      compiler_stats_num_field('bytes allocated',
                               [(wordsize(64), 165890392, 10)])
      This required the programmer to give the expected values and a tolerance
      deviation (percentage). With this patch, the above statements are
      replaced with:
      collect_stats('peak_megabytes_allocated', 5)
      collect_compiler_stats('bytes allocated', 10)
      So that programmer must only enter which metrics to test and a tolerance
      deviation. No expected value is required. CircleCI will then run the
      tests per test environment and record the metrics to a git note for that
      commit and push them to the git.haskell.org ghc repo. Metrics will be
      compared to the previous commit. If they are different by the tolerance
      deviation from the *.T file, then the corresponding test will fail. By
      adding to the git commit message e.g.
       # Metric (In|De)crease <metric(s)> <options>: <tests>
      Metric Increase ['bytes allocated', 'peak_megabytes_allocated'] \
               (test_env='linux_x86', way='default'):
          Test012, Test345
      Metric Decrease 'bytes allocated':
      Metric Increase:
      This will allow the noted changes (letting the test pass). Note that by
      omitting metrics or options, the change will apply to all possible
      metrics/options (i.e. in the above, an increase for all metrics in all
      test environments is allowed for Test711)
      phabricator will use the message in the description
      Reviewers: bgamari, hvr
      Reviewed By: bgamari
      Subscribers: rwbarton, carter
      GHC Trac Issues: #12758
      Differential Revision: https://phabricator.haskell.org/D5059