What's the equivalent of cache_clear_all()? What's the equivalent of cache_clear_all() in Drupal 8?
You can use Cache api. It would be somthing like 

\Drupal::cache('bin')-&gt;invalidateAll();


Or if you want to remove the entries and not just invalidate them:

\Drupal::cache('bin')-&gt;delete('variables') 


where bin is a valid cache bin such as menu, render, page ...etc.