Red Hat ENTERPRISE LINUX 3 - DEVELOPER TOOLS GUIDE Guide de l'utilisateur Page 87
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- MARQUE LIVRES
Noté. / 5. Basé sur avis des utilisateurs
ftrace
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8.60%40634845107 libxml2.so.2.7.6 [.] xmlXPathCompOpEval
4.63%21864091080 libxml2.so.2.7.6 [.] xmlXPathReleaseObject
2.73%12919672281 libxml2.so.2.7.6 [.] xmlXPathNodeSetSort__internal_alias
2.60%12271959697 libxml2.so.2.7.6 [.] valuePop
2.41%11379910918 libxml2.so.2.7.6 [.] xmlXPathIsNaN__internal_alias
2.19%10340901937 libxml2.so.2.7.6 [.] valuePush__internal_alias
6.7. ftrace
The ftrace framework provides users with several tracing capabilities, accessible through an
interface much simpler than SystemTap's. This framework uses a set of virtual files in the debugfs file
system; these files enable specific tracers. The ftrace function tracer simply outputs each function
called in the kernel in real time; other tracers within the ftrace framework can also be used to
analyze wakeup latency, task switches, kernel events, and the like.
You can also add new tracers for ftrace, making it a flexible solution for analyzing kernel events.
The ftrace framework is useful for debugging or analyzing latencies and performance issues that
take place outside of user-space. Unlike other profilers documented in this guide, ftrace is a built-in
feature of the kernel.
6.7.1. Using ftrace
The Red Hat Enterprise Linux 6 kernels have been configured with the CONFIG_FTRACE=y option.
This option provides the interfaces needed by ftrace. To use ftrace, mount the debugfs file
system as follows:
mount -t debugfs nodev /sys/kernel/debug
All the ftrace utilities are located in /sys/kernel/debug/tracing/. View the /sys/kernel/
debug/tracing/available_tracers file to find out what tracers are available for your kernel:
cat /sys/kernel/debug/tracing/available_tracers
power wakeup irqsoff function sysprof sched_switch initcall nop
To use a specific tracer, write it to /sys/kernel/debug/tracing/current_tracer. For
example, wakeup traces and records the maximum time it takes for the highest-priority task to be
scheduled after the task wakes up. To use it:
echo wakeup > /sys/kernel/debug/tracing/current_tracer
To start or stop tracing, write to /sys/kernel/debug/tracing/tracing_on, as in:
echo 1 > /sys/kernel/debug/tracing/tracing_on (enables tracing)
echo 0 > /sys/kernel/debug/tracing/tracing_on (disables tracing)
The results of the trace can be viewed from the following files:
/sys/kernel/debug/tracing/trace
This file contains human-readable trace output.
/sys/kernel/debug/tracing/trace_pipe
This file contains the same output as /sys/kernel/debug/tracing/trace, but is meant to
be piped into a command. Unlike /sys/kernel/debug/tracing/trace, reading from this file
consumes its output.
- Red Hat Enterprise Linux 6 1
- Developer Guide 1
- Enterprise Linux 6 3
- Edition 0 3
- 1. Document Conventions 7
- 1.2. Pull-quote Conventions 8
- 1.3. Notes and Warnings 9
- 2.1. Do You Need Help? 9
- 2.2. We Need Feedback! 10
- Introduction to Eclipse 11
- 1.2. Help In Eclipse 13
- 1.3. Development Toolkits 15
- Environment (IDE) 17
- 2.2. Useful Hints 21
- 2.2.2. libhover Plug-in 27
- 2.2.2.1. Setup and Usage 28
- Libraries and Runtime Support 31
- 3.2.1. API Compatibility 32
- 3.2.2. ABI Compatibility 32
- 3.2.3. Policy 32
- 3.2.4. Static Linking 33
- 3.3.1. The GNU C Library 33
- std::vector 37
- elements in any order 37
- 3.3.3. Boost 38
- 3.3.3.1. Boost Updates 39
- 3.3.3.2. Boost Documentation 40
- 3.3.4. Qt 41
- 3.3.4.2. Qt Creator 42
- 3.3.5.1. KDE4 Architecture 42
- 3.3.6. Python 44
- 3.3.7. Java 45
- 3.3.8. Ruby 46
- 3.3.9. Perl 47
- 3.3.9.3. Perl Documentation 48
- Compiling and Building 49
- 4.1.2. Language Compatibility 50
- 4.1.6. Running GCC 53
- 4.1.6.1. Simple C Usage 54
- 4.1.6.2. Simple C++ Usage 54
- 4.2. Distributed Compiling 60
- 4.3. Autotools 60
- 4.3.2. Configuration Script 61
- Debugging 63
- 5.2.1. Simple GDB 64
- 5.2.2. Running GDB 65
- 5.2.4. Forked Execution 68
- 5.2.5. Threads 68
- 5.2.7. GDB Documentation 68
- 5.4. Python Pretty-Printers 69
- Highly Customizable 70
- Easy to Learn 70
- Profiling 71
- 6.2. Valgrind 72
- 6.2.2. Using Valgrind 73
- 6.3. OProfile 74
- 6.3.2. Using OProfile 75
- 6.4. SystemTap 76
- Unprivileged Users) 78
- 6.5. Eclipse-Callgraph 79
- Chapter 6. Profiling 80
- 6.5.2. The Callgraph View 81
- Go to Code 84
- 6.6.1. Perf Tool Commands 85
- 6.6.2. Using Perf 85
- 6.7. ftrace 87
- 6.7.2. ftrace Documentation 88
- Appendix A. Revision History 89
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