Profile CPU performance at 1-minute intervals, compare it to reported load average

profile.php

<?php

$file = dirname(__FILE__) . '/profile.csv';

$out = fopen($file, 'a');

$load = @file_get_contents('/proc/loadavg');
$load = preg_split('/ /', $load);
$load = $load[0];

// Do some math, see how long it really takes
$n = 2308974928374092387430948723;

$now = date('Y-m-d H:i');

$start = microtime();

for ($i = 0; ($i < 10000); $i++)
{
  $n = $n * 4 % 3;
}

$end = microtime();

// Column 1 is the time, column 2 is the reported load average,
// column 3 is how long it really took to do the math. If they
// don't correlate very well then some third factor, like
// heavy load elsewhere in the system virtualizing this VM,
// may be at fault

fputcsv($out, array($now, $load, $end-$start));

fclose($out);