Blowfish hash cost : time estimates

blowfish.php

<?php

// Some simple benchmark functions

function starttime() {
    $r = explode( ' ', microtime() );
    $r = $r[1] + $r[0];
    return $r;
}
function endtime($starttime) {
    $r = explode( ' ', microtime() );
    $r = $r[1] + $r[0];
    $r = round($r - $starttime,4);
    return $r.' seconds'."\n";
}

// Let's hash with different costs and see the order of computational effort it makes

$password = "This is my p4ssw0rd !";

$start = starttime();
var_dump(password_hash($password, PASSWORD_BCRYPT, ['cost' => 4]));
echo endtime($start); // 0.0013 seconds

$start = starttime();
var_dump(password_hash($password, PASSWORD_BCRYPT)); // with default 10
echo endtime($start); // 0.0777 seconds

$start = starttime();
var_dump(password_hash($password, PASSWORD_BCRYPT, ['cost' => 11]));
echo endtime($start); // 0.1486 seconds

$start = starttime();
var_dump(password_hash($password, PASSWORD_BCRYPT, ['cost' => 15]));
echo endtime($start); // 2.3974 seconds