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/****************************************************************************
**
** Copyright (c) 2014 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of Qt Creator
**
**
** GNU Free Documentation License
**
** Alternatively, this file may be used under the terms of the GNU Free
** Documentation License version 1.3 as published by the Free Software
** Foundation and appearing in the file included in the packaging of this
** file.
**
**
****************************************************************************/
// **********************************************************************
// NOTE: the sections are not ordered by their logical order to avoid
// reshuffling the file each time the index order changes (i.e., often).
// Run the fixnavi.pl script to adjust the links to the index order.
// **********************************************************************
/*!
\contentspage index.html
\previouspage creator-valgrind-overview.html
\page creator-analyzer.html
\nextpage creator-cache-profiler.html
\title Detecting Memory Leaks
You can use the Memcheck tool included in the
Valgrind tool suite to detect
problems that are related to memory management in applications.
\note Memcheck is supported locally on Linux and Mac OS. You can run it on
a remote host from Windows.
After you download and install Valgrind tools, you can use Memcheck from
\QC.
To analyze applications:
\list 1
\li In the \gui Projects mode, select a debug build configuration.
\li Select \gui Analyze to open the \gui Analyze mode.
\li Select \gui {Analyze Memory} on the toolbar.
\li Select the
\inlineimage qtcreator-analyze-start-button.png "Start button"
button to start the application.
\li Use the application to analyze it.
\li Select the
\inlineimage qtcreator-debug-button-stop.png "Stop button"
button to view the results of the analysis in the
\gui {Analysis} view.
\endlist
While the application is running, Memcheck checks all reads and writes of
memory and intercepts calls that allocate or free memory or create or
delete memory blocks. When you stop Memcheck, it displays the results in
the \gui Analysis view. Click a line to view where a memory leak
occurred and a stack trace that shows what caused it.
\image analyzer-issues.png "Analysis view"
Move the mouse on a row to view more information about the function.
For more information about using Memcheck, see
\l{http://valgrind.org/docs/manual/quick-start.html#quick-start.mcrun}
{Interpreting Memcheck's Output} in the Valgrind documentation.
\section1 Selecting Options for Memory Analysis
You can specify analyzer settings either globally for all projects or
separately for each project in the \l{Specifying Run Settings}{run settings}
of the project.
Stack traces can get quite large and confusing, and therefore, reading them
from the bottom up can help. If the stack trace is not big enough or it is
too big, select \gui {Tools > Options > Analyzer}.
Define the length of the stack trace in the \gui {Backtrace frame count}
field.
\image qtcreator-valgrind-memcheck-options.png "Memory Analysis options"
Memcheck also reports uses of uninitialised values, most commonly with the
message \gui {Conditional jump or move depends on uninitialised value(s).}
To determine the root cause of these errors, the \gui {Track origins of
uninitialized memory} check box is selected by default. You can deselect it
to make Memcheck run faster.
Memcheck searches for memory leaks when the client application finishes. To
view the amount of leaks that occurred, select \gui {Summary Only} in the
\gui {Check for leaks on finish} field. To also view details of each leak,
select \gui Full.
\section2 Showing Reachable and Indirectly Lost Blocks
\e Reachable blocks are blocks that are pointed at by a pointer or chain
of pointers and that might have been freed before the application exited.
\e {Indirectly lost} blocks are considered lost because all the blocks that
point to them are themselves lost. For example, all the children of a lost
root node are indirectly lost.
By default, Memcheck does not report reachable and indirectly lost blocks.
To have them reported, select the \gui {Show reachable and indirectly lost
blocks}.
\section2 Suppressing Errors
Memcheck detects numerous problems in the system libraries, such as the C
library, which come pre-installed with your OS. As you cannot easily fix
them, you want to suppress them. Valgrind reads a list of errors to suppress
at startup. A default suppression file is created by the ./configure script
when the system is built.
You can write your own suppression files if parts of your project contain
errors you cannot fix and you do not want to be reminded of them. Click
\gui Add in the \gui {Memory Analysis} dialog to add the suppression files.
For more information about writing suppression files, see
\l{http://valgrind.org/docs/manual/manual-core.html#manual-core.suppress}
{Suppressing Errors} in the Valgrind documentation.
*/
/*!
\contentspage index.html
\previouspage creator-analyzer.html
\page creator-cache-profiler.html
\nextpage creator-running-valgrind-remotely.html
\title Profiling Function Execution
You can use the Callgrind tool included in the
\l{http://valgrind.org/info/tools.html}{Valgrind tool suite} to detect
problems that are related to executing functions.
After you download and install Valgrind tools, you can use Callgrind from
\QC.
\note Callgrind is supported locally on Linux and Mac OS. You can run
it on a remote Linux machine or device from any development machine.
To analyze applications:
\list 1
\li In the \gui Projects mode, select a release build configuration.
\li Select \gui Analyze to open the \gui Analyze mode.
\li Select \gui Profile on the toolbar.
\li Select the
\inlineimage qtcreator-analyze-start-button.png "Start button"
button to start the application.
\li Use the application to analyze it.
\li Select the
\inlineimage qtcreator-debug-button-stop.png "Stop button"
button to view the results of the analysis in the \gui Profile
view.
\endlist
Callgrind records the call history of functions that are executed when the
application is run. It collects the number of instructions that are
executed, their relationship to source lines, the relationships of the
caller and callee between functions, and the numbers of such calls. You can
also use cache simulation or branch prediction to gather information about
the runtime behavior of an application.
Double-click a function to view information about the calling functions in
the \gui Callers view and about the called functions in the \gui Callees
view.
Since the run-time characteristics of debug and release
\l{glossary-build-config}{build configurations}
differ significantly, analytical findings for one build configuration may or
not be relevant for the other. Profiling a debug build
often finds a major part of the time being spent in low-level
code like container implementations, while the same code
does not show up in the profile of a release build of the
same application due to inlining and other optimizations
typically done there.
Many recent compilers allow you to build an optimized application
with debug information present at the same time. Typical
options for GCC are for instance \c{-g -O2}. It is
advisable to use such a setup for Callgrind profiling.
\image qtcreator-valgrind-callgrind.png "Profile view"
\section1 Selecting Profiling Options
You can specify analyzer settings either globally for all projects or
separately for each project in the \l{Specifying Run Settings}{run settings}
of the project.
To specify settings for Valgrind, select \gui {Tools > Options >
Analyzer}. The \gui {Profiling Options} group contains Callgrind options.
\image qtcreator-valgrind-callgrind-options.png "Valgrind options"
In the \gui {Result view: Minimum event cost}
field, limit the amount of results the profiler gives you to increase
profiler performance.
You can collect information about the system call times and the number of
global bus events of the event type \c Ge that are executed.
\section2 Enabling Full Cache Simulation
By default, only instruction read accesses (Ir) are counted. To fully
simulate the cache, select the \gui {Enable cache simulation} check box.
This enables the following additional event counters:
\list
\li Cache misses on instruction reads (I1mr/I2mr)
\li Data read accesses (Dr) and related cache misses (D1mr/D2mr)
\li Data write accesses (Dw) and related cache misses (D1mw/D2mw)
\endlist
\section2 Enabling Branch Prediction Simulation
To enable the following additional event counters, select the
\gui {Enable branch prediction simulation} check box:
\list
\li Number of conditional branches executed and related predictor misses
(Bc/Bcm)
\li Executed indirect jumps and related misses of the jump address
predictor (Bi/Bim)
\endlist
*/
/*!
\contentspage index.html
\previouspage creator-cache-profiler.html
\page creator-running-valgrind-remotely.html
\nextpage creator-advanced.html
\title Running Valgrind Tools Remotely
\QC integrates Valgrind code analysis tools for detecting memory
leaks and profiling function execution. These tools are supported locally
only on Linux and Mac OS, but you can run them on a remote host from
Windows.
To run the Valgrind tools on a remote host over SSH:
\list 1
\li Select \gui {Analyze > Valgrind Memory Analyzer (Remote)} or
\gui {Valgrind Function Profiler (Remote)}.
\image qtcreator-valgrind-remote-settings.png "Start Analyzer dialog"
\li Specify the application to run and analyze, and the \l{glossary-buildandrun-kit}{kit}
to use.
\endlist
*/
|
