.. zephyr:code-sample:: profiling-perf
:name: Perf tool
Send perf samples to the host with console support
This application can be used to understand how to use the :ref:`profiling-perf`
tool.
Requirements
************
The Perf tool is currently implemented only for RISC-V and x86_64 architectures.
Usage example
*************
* Build and run the sample with:
.. zephyr-app-commands::
:zephyr-app: samples/subsys/profiling/perf
:board: qemu_riscv64
:goals: run
:compact:
* After the sample has started, enter the shell command:
.. code-block:: console
uart:~$ perf record <duration> <frequency>
This command will start a timer for *duration* milliseconds at *frequency* Hz.
* Wait for the completion message ``perf done!``, or ``perf buf override!`` if
the perf buffer size is smaller than required.
* Print the samples captured by perf in the terminal with the shell command:
.. code-block:: console
uart:~$ perf printbuf
The output should be similar to:
.. code-block:: console
Perf buf length 2046
0000000000000004
00000000001056b2
0000000000108192
000000000010052f
0000000000000000
....
000000000010052f
0000000000000000
* Copy the output into a file, for example :file:`perf_buf`.
* Generate :file:`graph.svg` with
:zephyr_file:`scripts/profiling/stackcollapse.py` and `FlameGraph`_:
.. _FlameGraph: https://github.com/brendangregg/FlameGraph/
.. code-block:: shell
python scripts/perf/stackcollapse.py perf_buf build/zephyr/zephyr.elf | <flamegraph_dir_path>/flamegraph.pl > graph.svg
Graph example
=============
.. image:: images/graph_example.svg
:align: center
:alt: graph example
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