package core_profiler

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Profiling library


Dune Dependency





Release v0.16.0

  • Updated internal binary protocol functions to support local allocation. Local allocation is an experimental compiler extension found at:

Old pre-v0.15 changelogs (very likely stale and incomplete)


  • Switched to ppx.

  • Minor adjustments to the command line of profiler_tool.exe:

    • Make '-%' an alias for '-percentile'

    • Make '-percentile' accept a comma-separated list of numbers

    • Add '-median' argument that is equivalent to '-percentile 50'


  • Changed delta timers and probes so they record the total amount of time/value change between each start and pause.


Initial release


Initial release


  • Solved a problem in which OCaml 4.02 was optimizing away benchmarks, making them meaningless.


  • fixed legacy format string


  • Added support for saving inline benchmark measurements to tabular files for easy loading into Octave.


  • Improved bench.mli's generated docs and added some usage examples.

    This also partly satisfies issue #3.

  • Added the ability to create groups of benchmarks with a common prefix.

    For example, the prefix "Perf" below is created in created using create_group:

    let command = Bench.make_command [
      Bench.Test.create ~name:"" (fun () ->
        ignore ( ()));
      Bench.Test.create_group ~name:"Perf" [
        Bench.Test.create ~name:"" ...

    and the output shows:

    Estimated testing time 7s (7 benchmarks x 1s). Change using -quota SECS.
    │ Name                                      │ Time/Run │ mWd/Run │ Percentage │
    │                                  │  41.38ns │   2.00w │     16.72% │
    │ Calibrator.calibrate                      │ 247.42ns │  32.00w │    100.00% │
    │ Perf/                              │   7.84ns │         │      3.17% │
    │ Perf/TSC.to_time                          │   9.35ns │   2.00w │      3.78% │
    │ Perf/TSC.to_time ( ())             │  13.22ns │   2.00w │      5.34% │
    │ Perf/TSC.to_nanos_since_epoch             │  10.83ns │         │      4.38% │
    │ Perf/TSC.to_nanos_since_epoch( ()) │  14.86ns │         │      6.00% │


  • Fixed a bug in Core_bench where the linear regression was sometimes supplied with spurious data.

    This showed up when doing custom regressions that allow for a non-zero y-intercept.


  • Exposed an extensible form of make_command so that inline-benchmarking and the other tools can add more commandline flags.

  • A significant rewrite of Core_bench.

    The rewrite provides largely the same functionality as the older version. The most visible external change is that the API makes it clear that Core_bench performs linear regressions to come up with its numbers. Further, it allows running user-specified multivariate regressions in addition to the built in ones.

    The underlying code has been cleaned up in many ways, some of which are aimed at improving the implementation of inline benchmarking (the BENCH syntax, which has not yet been released).


  • Columns that have a + prefix are now always displayed, whereas columns that don't are displayed only if they have meaningful data.

  • Added the ability to reload saved metrics (benchmark test data) so that bench can re-analyze them.


  • Added support for additional predictors like minor/major GCs and compactions, using multi-variable linear regression.

    Replaced linear regression with multi-variable linear regression. The original algorithm estimated the cost of a function f by using a linear regression of the time taken to run f vs the number of runs. The new version adds the ability to include additional predictors such as minor GCs, compactions etc.

    This allows a more fine-grained split-up of the running costs of a function, distinguishing between the time spent actually running f and the time spent doing minor GCs, major GCs or compactions.

  • Added a forking option that allows benchmarks to be run in separate processes.

    This avoids any influence (e.g. polluting the cache, size of live heap words) they might otherwise have on each other.


  • Changed -save to output compaction information.

  • Added indexed tests.

    These are benchmarks of the form int -> unit -> unit, which can be profiled for a list of user specified ints.


  • Report compaction stats


  • Added R^2 error estimation.

    Adding this metric should give us a sense of how closely the given values fit a line. Even dots that are fairly scattered can give tight confidence intervals. We would like to have to number to have a sense of how much noise we have.