Proofread howto/perf_profiling.rst by verhovsky · Pull Request #103530 · python/cpython

Expand Up @@ -15,9 +15,9 @@ information about the performance of your application. that aid with the analysis of the data that it produces.
The main problem with using the ``perf`` profiler with Python applications is that ``perf`` only allows to get information about native symbols, this is, the names of the functions and procedures written in C. This means that the names and file names of the Python functions in your code will not appear in the output of the ``perf``. ``perf`` only gets information about native symbols, that is, the names of functions and procedures written in C. This means that the names and file names of Python functions in your code will not appear in the output of ``perf``.
Since Python 3.12, the interpreter can run in a special mode that allows Python functions to appear in the output of the ``perf`` profiler. When this mode is Expand All @@ -28,8 +28,8 @@ relationship between this piece of code and the associated Python function using
.. note::
Support for the ``perf`` profiler is only currently available for Linux on selected architectures. Check the output of the configure build step or Support for the ``perf`` profiler is currently only available for Linux on select architectures. Check the output of the ``configure`` build step or check the output of ``python -m sysconfig | grep HAVE_PERF_TRAMPOLINE`` to see if your system is supported.
Expand All @@ -52,11 +52,11 @@ For example, consider the following script: if __name__ == "__main__": baz(1000000)
We can run ``perf`` to sample CPU stack traces at 9999 Hertz:: We can run ``perf`` to sample CPU stack traces at 9999 hertz::
$ perf record -F 9999 -g -o perf.data python my_script.py
Then we can use ``perf`` report to analyze the data: Then we can use ``perf report`` to analyze the data:
.. code-block:: shell-session
Expand Down Expand Up @@ -97,7 +97,7 @@ Then we can use ``perf`` report to analyze the data: | | | | | |--2.97%--_PyObject_Malloc ...
As you can see here, the Python functions are not shown in the output, only ``_Py_Eval_EvalFrameDefault`` appears As you can see, the Python functions are not shown in the output, only ``_Py_Eval_EvalFrameDefault`` (the function that evaluates the Python bytecode) shows up. Unfortunately that's not very useful because all Python functions use the same C function to evaluate bytecode so we cannot know which Python function corresponds to which bytecode-evaluating function. Expand Down Expand Up @@ -151,7 +151,7 @@ Instead, if we run the same experiment with ``perf`` support enabled we get: How to enable ``perf`` profiling support ----------------------------------------
``perf`` profiling support can either be enabled from the start using ``perf`` profiling support can be enabled either from the start using the environment variable :envvar:`PYTHONPERFSUPPORT` or the :option:`-X perf <-X>` option, or dynamically using :func:`sys.activate_stack_trampoline` and Expand Down Expand Up @@ -192,7 +192,7 @@ Example, using the :mod:`sys` APIs in file :file:`example.py`: How to obtain the best results ------------------------------
For the best results, Python should be compiled with For best results, Python should be compiled with ``CFLAGS="-fno-omit-frame-pointer -mno-omit-leaf-frame-pointer"`` as this allows profilers to unwind using only the frame pointer and not on DWARF debug information. This is because as the code that is interposed to allow ``perf`` Expand Down