- If all QueueingHintFn return QueueSkip, it puts this pod back to the unschedulable pod pool
  
  Having appropriate QueueingHintFn contributes to reducing useless retries and thus improves the overall scheduler's performance.
  
  **How can I migrate?**
  
  For backward compatibility, nil `QueueingHintFn` is treated as always returning QueueAfterBackoff.