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Doc: Add info about troubleshooting Performance Analyzer

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Fixes: QTCREATORBUG-27707
Change-Id: Icd2c5ad8ef79ecb7a2a2e37574a269e24bf55e71
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: hjk <hjk@qt.io>
This commit is contained in:
Leena Miettinen
2022-07-04 14:21:13 +02:00
parent 87bdbb993e
commit 0caa9b4cee
2 changed files with 37 additions and 5 deletions
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10
README.md
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@@ -147,6 +147,16 @@ like Qt and LLVM, additionally run
cmake --install . --prefix /path/to/qtcreator_install --component Dependencies
### Performance Analyzer
If you have not installed Qt with the Maintenance Tool, you must
either set the path to the `perfparser` executable as a value of
the `PERFPROFILER_PARSER_FILEPATH` environment variable or copy
the executable to from the Qt Creator installation directory to
the build directory. That is, copy it from
`/path/to/qtcreator_install/Tools/QtCreator/libexec/qtcreator/` to
/path/to/qtcreator_buid/libexec/qtcreator/`.
## Getting LLVM/Clang for the Clang Code Model
The Clang code model uses `Clangd` and the ClangFormat plugin depends on the

32
doc/qtcreator/src/analyze/cpu-usage-analyzer.qdoc
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@@ -1,6 +1,6 @@
/****************************************************************************
**
** Copyright (C) 2021 The Qt Company Ltd.
** Copyright (C) 2022 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the Qt Creator documentation.
@@ -471,14 +471,23 @@
The Performance Analyzer might fail to record data for the following reasons:
\list 1
\li Perf events may be globally disabled on your system. The
preconfigured \l Boot2Qt images come with perf events enabled. For
a custom configuration you need to make sure that the file
\list
\li Perf events may be globally disabled on your system.
The preconfigured \l Boot2Qt images come with perf events enabled.
For a custom configuration you need to make sure that the file
\c {/proc/sys/kernel/perf_event_paranoid} contains a value smaller
than \c {2}. For maximum flexibility in recording traces you can
set the value to \c {-1}. This allows any user to record any kind
of trace, even using raw kernel trace points.
The way to enable Perf events depends on your Linux distribution.
On some distributions, you can run the following command with
root (or equivalent) privileges:
\badcode
echo -e "kernel.perf_event_paranoid=-1\nkernel.kptr_restrict=0" | sudo tee /etc/sysctl.d/10-perf.conf
\endcode
\li The connection between the target device and the host may not be
fast enough to transfer the data produced by Perf. Try modifying
the values of the \uicontrol {Stack snapshot size} or
@@ -501,8 +510,21 @@
drives the sampling from software. After the sampling has failed,
reboot the device. The kernel may have disabled important parts of
the performance counters system.
\li Perf might not be installed. The way to install it depends on your
Linux distribution. For example, you might try the following
commands:
\list
\li On Ubuntu 22.04:
\c {sudo apt install linux-tools-$(uname -r)}
\li On Debian:
\c {apt install linux-perf}
\endlist
\endlist
Output from the helper program that processes the data is displayed in
\l{Viewing Output}{General Messages}.
Some information is displayed in \l {Application Output} even if the
Performance Analyzer displays error messages.
*/