c - In PHP, how to measure the time a request spent utilizing hard disk? -

is there way measure amount/length of time web request spends doing i/o?

by that, mean actual amount of time current thread (or it's delegation) has spent utilizing hardware.

as measuring cpu time, there's function getrusage() it:

<?php  $a = getrusage(); f(); $b = getrusage();  $sec = ($b['ru_utime.tv_sec'] - $a['ru_utime.tv_sec']) + ($b['ru_stime.tv_sec'] - $a['ru_stime.tv_sec']); echo 'it took ~' . $sec . 's of cpu time.';  function f(){     for($x=0;$x<120000000;++$x){         // busy loop     } } 

is there such function measuring i/o?

sample usage of said function:

<?php  $credits_remaining = 8500;  $a = time_spent_on_hard_disk_so_far(); get_file_from_hard_disk($credits_remaining); // limit request $credits_remaining number of seconds $b = time_spent_on_hard_disk_so_far(); $time_spent = $b - $a;  echo "time spent on hard disk: ", $time_spent; $credits_remaining -= $time_spent; 

(a c solution fine, long can call php without suffering severe overheads.)

in particular scenario, i'd microtime[stamp] before start operation(s), difference microtime[stamp], store results in array metadata explains metric refers to, , store information in data store, somewhere (database, txt file, session, etc.).

it's best (easiest) way track kind of information , have code maintain portability across numerous operating environments.

/**  *  micro time  *  *  returns current (epoch) time micro seconds.  *  *  @param [in] $elapsed %ref% of difference since last execution  *  @return | float time micro seconds epoch  */ function microtime(&$elapsed = null) {      static $previous = null;      list($micro, $epoch) = explode(" ", microtime());      $now = round(floatval($epoch.substr($micro, 1)), 3);      if ($previous) {         $elapsed = round($now - $previous,3);     }      $previous = $now;      return $now;  }