private function create_small_files() {
        $count = self::$paramsmallfilecount[$this->size];
        $this->log('createsmallfiles', $count, true);

        // Create resource with default textfile only.
        $resourcegenerator = $this->generator->get_plugin_generator('mod_resource');
        $record = array('course' => $this->course,
                'name' => get_string('smallfiles', 'tool_generator'));
        $options = array('section' => 0);
        $resource = $resourcegenerator->create_instance($record, $options);

        // Add files.
        $fs = get_file_storage();
        $context = context_module::instance($resource->cmid);
        $filerecord = array('component' => 'mod_resource', 'filearea' => 'content',
                'contextid' => $context->id, 'itemid' => 0, 'filepath' => '/');
        for ($i = 0; $i < $count; $i++) {
            $filerecord['filename'] = 'smallfile' . $i . '.dat';

            // Generate random binary data (different for each file so it
            // doesn't compress unrealistically).
            $data = random_bytes_emulate($this->limit_filesize(self::$paramsmallfilesize[$this->size]));

            $fs->create_file_from_string($filerecord, $data);
            $this->dot($i, $count);
        }

        $this->end_log();
    }