Upgraded Tool Does Kernel-Level Debugging For Real-Time Linux

Oct. 2, 2000

The Linux Trace Toolkit (LTT) now supports kernel-level debugging. It has been available for application-level debugging for some time, but real-time developers had to contend with basic debugging tools. This version of LTT also supports the Linux...

William G. Wong

LTT is an open-source project supported by Opersys Inc. of Montreal, Canada, and Lineo Inc. of Lindon, Utah. It's distributed under the GNU General Public License, making it freely available to developers. As a graphical tool, it dynamically displays system performance information (see the figure). It can be used to determine what process was accessing hardware in a particular time slice. Also, it can highlight I/O device-driver latencies or application dependence on device drivers. It's especially useful in analyzing syncrhonization problems.

Converting regular Linux applications to hard real-time applications under RTAI requires one call, rt_make_hard_real_time(). But making sure the application does what it's intended to do under these constraints is now much easier. LTT support currently works in a single-processor environment. The support hooks have not been added in the multiprocessor Linux kernel. This is a limitation with RTAI, LTT, and the multiprocessing support. LTT already works in this environment for regular applications.

A minor change to the LTT trace-file format makes it incompatible with prior versions, though. On the plus side, the binary format is smaller, which is very handy because tracing over long periods of time can generate rather large files. The binary encoding also im-proves performance.

For more information about the LTT, visit www.opersys.com/ LTT/.

About the Author

William G. Wong | Senior Content Director - Electronic Design and Microwaves & RF

I am Editor of Electronic Design focusing on embedded, software, and systems. As Senior Content Director, I also manage Microwaves & RF and I work with a great team of editors to provide engineers, programmers, developers and technical managers with interesting and useful articles and videos on a regular basis. Check out our free newsletters to see the latest content.

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I earned a Bachelor of Electrical Engineering at the Georgia Institute of Technology and a Masters in Computer Science from Rutgers University. I still do a bit of programming using everything from C and C++ to Rust and Ada/SPARK. I do a bit of PHP programming for Drupal websites. I have posted a few Drupal modules.

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