function page_etime($pagestartime,$median){
	/*
	$pagestartime取页面头部的microtime();
	$median为时间位数，请使用常量
	*/
	$pageendtime = microtime();
	$starttime = explode(" ",$pagestartime);
	$endtime = explode(" ",$pageendtime);
	$totaltime = $endtime[0]-$starttime[0]+$endtime[1]-$starttime[1];
	$timecost = sprintf("%s",$totaltime);
	$time =round($timecost,$median);
	return $time;
}

示例:
echo page_etime($startime,7);

$geshi = new geshi($code, $type);
$geshi->set_header_type(GESHI_HEADER_DIV);
$geshi->enable_line_numbers(GESHI_NORMAL_LINE_NUMBERS); 
$html = $geshi->parse_code();