Wikimedia Bugzilla is closed!

While the documentation claims this parameter to be still in use, it is in fact not used by the software. It's fairly simple to implement it.

Example for Profiler.php:
global $wgProfileLimit;
if (((float) ($elapsed * 1000)) >= $wgProfileLimit) {
  $prof .= sprintf($format, substr($fname, 0, $nameWidth), $calls, (float) ($elapsed * 1000), (float) ($elapsed * 1000) / $calls, $percent, $memory, ($this->mMin[$fname] * 1000.0), ($this->mMax[$fname] * 1000.0), $this->mOverhead[$fname]);
}