to set file size limit in upload large file

1. set in (.htaccess)
php_value upload_max_filesize 3G
php_value post_max_size 3G

2. set in upload.php action
<?php
ini_set('upload_max_filesize', '3G');
ini_set('post_max_size', '3G');

$uploaddir = 'upload/';

$file = basename($_FILES['userfile']['name']);
$uploadfile = $uploaddir . $file;

if (move_uploaded_file($_FILES['userfile']['tmp_name'], $uploadfile)) {
echo "OK";
}
else {
echo "ERROR";
}
?>

3. form
<form method="post" enctype="multipart/form-data" action="upload.php">
<input type="file" id="userfile" size="20" name="userfile">
<input type="submit" value="Upload" name="submit">
</form>