Hello,

Yesterday I have been made aware of a built-in profiling tool in MediaWiki. I played a bit with it and wondered if I could implement such a tool for another project.

This afternoon I finally found a good way of profiling mediawiki cpu usage, a picture of the result is at: http://www.twenkill.net/phpprofiler.png (might be unavailable depending of my home connection status).

Using debian GNU/Linux, following is a little howto to get the same window opening on your screen.

1/ PROFILER

Install the profiling tool: apt-get install php4-apd To enable profiling in mediawiki edit your index.php file and insert at top: apd_set_pprof_trace();

Now each time a web request is made on your website, a file pprof.<apachepid> will be generated in /var/log/php4-apd/

This is a serious performance eater and should only be enable when you need profiling outputs !

2/ GUI FRONTEND

The gui frontend I use is Kcachegrind: apt-get install kcachegrind . As far as I understand, it uses Caltree profiling tool and Valgrind to make a graphical representation of a C software.

KCacheGrind isn't able to read pprof file format so you will have to convert it. A script is available at: http://cvs.php.net/co.php/pecl/apd/pprof2calltree?r=1.3 Eventually edit it so it looks like /usr/bin/pprof.

Then convert the pprof file: $ pprof2calltree -f pprof.29539 Writing kcachegrind compatible output to cachegrind.out.pprof.29539 $ ls cachegrind.out.pprof.29539 pprof.29539 $

If pprof2calltree start outputing lot of lines, you need to raise the memory usage limit in your cgi php.ini file ( /etc/php4/cgi/php.ini ).

Now launch kcachegrind: $ kcachegrind cachegrind.out.pprof.29539

Note: You will need the graphwiz library to generate the call maps: apt-get install graphwiz.

Enjoy ! :o)