A memory management unit responds to an invalidate by class command by identifying a marker for a class of cache entries that the invalidate by class command is meant to invalidate. The memory management unit stores the active marker as a retired marker and then sets the active marker to the next available marker. Thereafter, the memory management sends an acknowledgement signal (e.g., to the operating system) while invalidating the cache entries having the class and the retired marker in the background. By correlating markers with classes of cache entries, the memory management can more quickly respond to class invalidation requests.