A disk drive comprises non-volatile rotatable media and a controller operatively coupled to the non-volatile rotatable media. The controller is configured to receive a series of host commands to be executed by the controller and generate a command execution sequence comprising the series of host commands. A task manager, integral or coupled to the controller, is configured to receive a plurality of background tasks comprising a least two priority background tasks to be executed by the controller along with execution of the series of host commands, and insert one or more of the at least two priority background tasks into the command execution sequence while maintaining a specified ratio of priority background task execution and host command execution substantially constant. The controller is configured to execute the command execution sequence with the one or more inserted priority background tasks.