最便宜也是最麻烦的方法是在代码中想要进行基准测试的地方进行microtime()调用。在数据库查询之前和之后执行它，从脚本执行时间的其余部分中删除这些持续时间就很简单了。

提示:PHP执行时间很少会导致脚本超时。如果一个脚本超时，它几乎总是调用外部资源。

PHP微时间文档: http://us.php.net/microtime

return microtime(true) - $_SERVER["REQUEST_TIME_FLOAT"];

developerfusion.com的Gringod给出了一个很好的答案:

<!-- put this at the top of the page --> 
<?php 
   $mtime = microtime(); 
   $mtime = explode(" ",$mtime); 
   $mtime = $mtime[1] + $mtime[0]; 
   $starttime = $mtime; 
;?> 

<!-- put other code and html in here -->


<!-- put this code at the bottom of the page -->
<?php 
   $mtime = microtime(); 
   $mtime = explode(" ",$mtime); 
   $mtime = $mtime[1] + $mtime[0]; 
   $endtime = $mtime; 
   $totaltime = ($endtime - $starttime); 
   echo "This page was created in ".$totaltime." seconds"; 
;?>

从(http://www.developerfusion.com/code/2058/determine-execution-time-in-php/)

这里列出了几种方法。但每个人都有自己的优点和缺点。而且(在我看来)所有较长的答案的可读性都很糟糕。

所以我决定把这些都放在一个答案中，这是容易使用和阅读的。

使用

$start = get_timers();
for( $i = 0; $i < 100000; $i++ ){
  // Code to check
}
$end = get_timers();
display_timer_statistics( $start, $end );

函数定义

function display_timer_statistics( $start_timers, $end_timers ){

    // Settings
    $key_width = '100px';
    $decimals = 4;
    $decimals_wallclock = $decimals;
    $decimals_request_time_float = $decimals;

    // Variables
    $start_resource_usage_timer = $start_timers[0];
    $start_wallclock = $start_timers[1];
    $end_resource_usage_timer = $end_timers[0];
    $end_wallclock = $end_timers[1];

    // # User time
    // Add seconds and microseconds for the start/end, and subtract from another
    $end_user_time_seconds = $end_resource_usage_timer["ru_utime.tv_sec"]*1000;
    $end_user_time_microseconds = intval($end_resource_usage_timer["ru_utime.tv_usec"]/1000);
    $start_user_time_seconds = $start_resource_usage_timer["ru_utime.tv_sec"]*1000;
    $start_user_time_microseconds = intval($start_resource_usage_timer["ru_utime.tv_usec"]/1000);
    $total_user_time = ($end_user_time_seconds + $end_user_time_microseconds) - ($start_user_time_seconds + $start_user_time_microseconds);

    // # System time
    // Add seconds and microseconds for the start/end, and subtract from another
    $end_system_time_seconds = $end_resource_usage_timer["ru_stime.tv_sec"]*1000;
    $end_system_time_microseconds = intval($end_resource_usage_timer["ru_stime.tv_usec"]/1000);
    $start_system_time_seconds = $start_resource_usage_timer["ru_stime.tv_sec"]*1000;
    $start_system_time_microseconds = intval($start_resource_usage_timer["ru_stime.tv_usec"]/1000);
    $total_system_time = ($end_system_time_seconds + $end_system_time_microseconds) - ($start_system_time_seconds + $start_system_time_microseconds);

    // Wallclock
    $total_wallclock_time = number_format( ( $end_wallclock - $start_wallclock), $decimals_wallclock );

    // Server request_time_float
    $request_time_float = microtime(true) - $_SERVER["REQUEST_TIME_FLOAT"];
    $request_time_float = number_format( $request_time_float, $decimals_request_time_float );

    // Print
    $span_start = "<span style='width: $key_width; display: inline-block;'>";
    $span_end = "</span>";

    $output = "# RUNTIME AND TIMERS " . PHP_EOL ;
    $output .= PHP_EOL;
    $output .= $span_start . $total_user_time . $span_end . " User time (utime)" . PHP_EOL;
    $output .= $span_start . $total_system_time . $span_end . " System time (stime)" . PHP_EOL;
    $output .= PHP_EOL;
    $output .= $span_start . $total_wallclock_time . $span_end . " Wallclock" . PHP_EOL;
    $output .= PHP_EOL;
    $output .= $span_start . $request_time_float . $span_end . " REQUEST_TIME_FLOAT" . PHP_EOL . PHP_EOL . PHP_EOL;

    echo nl2br( $output );
}

function get_timers(){
    return [ getrusage(), microtime( true ) ];
}

术语表

这些都是从PHP文档中获取的

挂钟=花了多长时间 ru =资源使用率 utime =用户使用的时间 stime =使用的系统时间 tv_sec =秒。 tv_usec =以微秒计。 电视= ??不知道

如果你需要的是挂钟时间，而不是CPU执行时间，那么计算起来很简单:

//place this before any script you want to calculate time
$time_start = microtime(true); 

//sample script
for($i=0; $i<1000; $i++){
 //do anything
}

$time_end = microtime(true);

//dividing with 60 will give the execution time in minutes otherwise seconds
$execution_time = ($time_end - $time_start)/60;

//execution time of the script
echo '<b>Total Execution Time:</b> '.$execution_time.' Mins';
// if you get weird results, use number_format((float) $execution_time, 10) 

注意，这将包括PHP等待外部资源(如磁盘或数据库)的时间，而max_execution_time没有使用这个时间。

当PHP中有闭包功能时，为什么我们不从中获益呢?

function startTime(){
    $startTime = microtime(true);
    return function () use ($startTime){
        return microtime(true) - $startTime;
    };
}

现在，在上述函数的帮助下，我们可以像这样跟踪时间

$stopTime = startTime();
//some code block or line
$elapsedTime = $stopTime();

每次调用startTime函数都会启动一个单独的时间跟踪器。所以你可以想启动多少就启动多少，也可以在任何你想要的地方停止它们。