Pagination not working

Hi!

I’ve got an issue with this plugin. This is how my loop looks like:

<?php
						$args = array( 'order'=> 'desc' );
						$myposts = get_posts( $args );
						foreach ( $myposts as $post ) : setup_postdata( $post ); ?>
							<div class="row single-post">
								<div class="col-lg-2">
										<div class="date"><?php the_time('d.m.Y'); ?></div>
								</div>
								<div class="col-lg-9 content">
									<?php the_post_thumbnail('post-thumbnail', array( 'class' => "img-responsive post-image")); ?>
									<h2><?php echo get_the_title(); ?></h2>
									<p class="single-content"><?php the_excerpt(); ?></p>
									<div class="post-meta">
											<a href="<?php the_permalink(); ?>" title="Czytaj więcej" class="read-more">>> Czytaj więcej..</a>
											<p>Kategorie wpisu: <?php $category = get_the_category(); if($category[0]){ echo '<a href="'.get_category_link($category[0]->term_id ).'">'.$category[0]->cat_name.'</a>'; }	?></p>
									</div>
								</div>
							</div>

						<?php endforeach; wp_reset_postdata();?>
						<?php wp_pagenavi(); ?>

yet it shows all posts. Even if I use post_per_page e.g. 1, plugin dont divide posts into each page. why?

https://wordpress.org/plugins/wp-pagenavi/