WordPress at a glance
function is not described

wpmu_update_blogs_date() WP 3.0.0

Update the last_updated field for the current site.

Hooks in function
Return

Nothing (null).

Usage

wpmu_update_blogs_date();

Code of wpmu update blogs date: wp-includes/ms-blogs.php VER 5.0.3

<?php
function wpmu_update_blogs_date() {
	$site_id = get_current_blog_id();

	update_blog_details( $site_id, array( 'last_updated' => current_time( 'mysql', true ) ) );
	/**
	 * Fires after the blog details are updated.
	 *
	 * @since MU (3.0.0)
	 *
	 * @param int $blog_id Site ID.
	 */
	do_action( 'wpmu_blog_updated', $site_id );
}