Manual:$wgRequestTime

From mediawiki.org

Overview

Warning Warning: This is not an object variable, but is a global initialized by MediaWiki.

$wgRequestTime is a global microtime float that is initialized early in the engine that a lot of other times are computed relative to for logging, profiling, and debugging.

Examples

A snippet from Debug.php:

global $wgRequestTime;
return array(
    'time' => microtime( true ) - $wgRequestTime,
);