Callgrind

Callgrind (also known under the names Calltree and Cachegrind) is a call graph profiler (performance profiling tool) that runs on Linux x86. It builds on the Valgrind framework and has a graphical KDE frontend, KCachegrind.

The Valgrind user manual has a chapter of documentation. More documentation is available at KCachegrind, especially see the usage examples.

Installing

Debian

aptitude install valgrind kcachegrind graphviz

GraphViz is needed to see graphical call trees in KCachegrind.

Stock Debian/Etch has Valgrind v3.2.1, KCachegrind v0.4.6kde and GraphViz v2.8

SuSE

On SuSE 9.2, just install the kdesdk3-profile package (which will also install the valgrind package as a dependency). To see call graphs in kcachegrind, you also need to install the graphviz package.

Doing so installs Callgrind version 0.9.8, Valgrind version 2.2.0, and KCachegrind version 0.4.5kde on your machine.

Useful documentation is locally installed at /usr/share/doc/packages/valgrind/ct_main.html.

Profiling OpenOffice.org

old how-to, for reference

Template:Documentation/Note e.g., the callgrind utility in newer versions is a subtool invoked with valgrind --tool=callgrind instead.
The original author of this how-to is Stephan Bergmann.

TODO: Empty the original page http://tools.openoffice.org/profiling/callgrind-howto.html and make it forward to this page here. The OOo CVS ssh tunnel was down when I tried 2009-02-04T21:24+Z --erAck 23:16, 4 February 2009 (UTC)

No modification or instrumentation is necessary for profiling a sufficiently recent soffice.bin (I successfully tested this with OpenOffice.org 1.9.71). In the OpenOffice.org program directory, just execute

callgrind ./soffice.bin

When executing Java or some legacy dynamic libraries within soffice.bin, remember to extend LD_LIBRARY_PATH with the output of javaldx or with the OpenOffice.org program directory, respectively.

When callgrind is finished, it writes a file callgrind.out.pid. Use

kcachegrind callgrind.out.pid

to view it. I experienced the problem that the generated file is very small (around 500 byte) and does not contain the necessary information when profiling soffice.bin. In that case, it worked for me to execute

callgrind --separate-threads=yes ./soffice.bin

instead, which writes out individual files callgrind.out.pid.thread together with an empty callgrind.out.pid. Opening that empty callgrind.out.pid in kcachegrind automatically reads in all the individual thread files.

Detailed information at the source/assembler instruction level can be gathered by specifying the additional callgrind options --dump-instr=yes and --trace-jump=yes.

Limitations

It worked fine for me to profile soffice.bin, just starting it up and immediately closing it again with Ctrl-Q, and to similarly profile soffice.bin -swriter. However, callgrind easily runs out of memory when gathering data for longer runs, or runs in which more dynamic libraries are loaded.

One solution to this problem might be to only gather data for parts of an soffice.bin run, using the --instr-atstart and --collect-atstart options to callgrind, and using the callgrind_control tool (see the documentation). One caveat when using callgrind_control can be that it reports that no callgrind processes are running. In that case, it can work to manually place a callgrind.cmd file in the current working directory. That is, instead of

callgrind_control -i on

use

echo +Instrumentation > callgrind.cmd

and instead of

callgrind_control -d

use

echo Dump > callgrind.cmd

Using instrumentation only during operations that should be profiled also speeds up the startup of soffice.bin, so it is recommended to use this whenever the startup itself is not of interest.

Rather than using callgrind_control or callgrind.cmd, it is also possible to turn on and off instrumentation using macros within the source code itself. This is especially useful if callgrind fails to work without manually turning on and off instrumentation, or if the same code shall be profiled several times. The macro to turn instrumentation on is CALLGRIND_START_INSTRUMENTATION(), and the macro to turn it off is CALLGRIND_STOP_INSTRUMENTATION(). Both are contained in callgrind.h, which unfortunately is not installed with callgrind, but can be downloaded separately. callgrind.h includes valgrind.h, which is installed in /usr/include/valgrind already.