Mercurial > hg
changeset 44904:7ca1d635e4a6
rust: add a pointer for profiling to the README
As figuring out how to get useful profiles is not obvious.
Differential Revision: https://phab.mercurial-scm.org/D8603
| author | Valentin Gatien-Baron <valentin.gatienbaron@gmail.com> |
|---|---|
| date | Sat, 30 May 2020 11:36:30 -0400 |
| parents | 69d3ce00df99 |
| children | f330d6117a5b |
| files | rust/README.rst |
| diffstat | 1 files changed, 15 insertions(+), 0 deletions(-) [+] |
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--- a/rust/README.rst Sat May 30 10:28:46 2020 -0400 +++ b/rust/README.rst Sat May 30 11:36:30 2020 -0400 @@ -34,6 +34,21 @@ One day we may use this environment variable to switch to new experimental binding crates like a hypothetical ``HGWITHRUSTEXT=hpy``. +Profiling +========= + +Setting the environment variable ``RUST_LOG=trace`` will make hg print +a few high level rust-related performance numbers. It can also +indicate why the rust code cannot be used (say, using lookarounds in +hgignore). + +``py-spy`` (https://github.com/benfred/py-spy) can be used to +construct a single profile with rust functions and python functions +(as opposed to ``hg --profile``, which attributes time spent in rust +to some unlucky python code running shortly after the rust code, and +as opposed to tools for native code like ``perf``, which attribute +time to the python interpreter instead of python functions). + Developing Rust ===============