Install XHProf
--------------

To install XHProf, use the following commands as described on http://techportal.inviqa.com/2009/12/01/profiling-with-xhprof/:

  apt-get install php5-common
  pecl config-set preferred_state beta
  pecl install xhprof

If it complains because it can't find config.m4, you can still build the extension manually, using the following steps:

  wget http://pecl.php.net/get/xhprof-0.9.2.tgz
  tar xvf xhprof-0.9.2.tgz
  cd ./xhprof-0.9.2/extension/
  phpize
  ./configure --with-php-config=/usr/local/bin/php-config
  make
  make install
  make test

In the ./configure line above, if you use Ubuntu, it is likely you php-config
will have to be declared as /usr/bin/php-config. Check it with 
"which php-config".

Once you have XHProf installed, you should enable it. Open your php.ini or 
/etc/php5/conf.d/xhprof.ini and type:

  [xhprof]
  extension=xhprof.so
  xhprof.output_dir="/tmp"

If you use PHP 5.4, you will need to download xhprof from Git:
git clone git://github.com/facebook/xhprof.git
and sudo, make, make install

Combine with Chamilo
--------------------

To enable XHProf on your Chamilo, add this to your VirtualHost configuration
(assuming your Chamilo install is as /var/www/chamilo):

  php_value auto_prepend_file /var/www/chamilo/tests/xhprof/header.php
  php_value auto_append_file /var/www/chamilo/tests/xhprof/footer.php

Also check /var/www/chamilo/tests/xhprof/footer.php to update the sprintf
command to use the name of your host.