Command processing method and storage controller using the same

A storage controller, configured to access a rewritable non-volatile memory module and coupled to a host system, the storage controller comprising:

• a command sorter;
• a plurality of command queue managers, coupled to the command sorter;
• an arbitrator, coupled to the command queue managers;
• a timer, coupled to the arbitrator;
• and
• a processor, coupled to at least one of the command sorter, the command queue managers and the arbitrator, wherein
• the command sorter receives a plurality of I/O commands from the host system,
• the command sorter categorizes the I/O commands into a plurality of groups according to a processor effort index of the I/O commands,
• the arbitrator selects a first group from the groups, resets a timer and obtains an expiration time corresponding to the first group according to the I/O commands of the first group, and the processor executes the 1/0 commands of the first group,
• the arbitrator selects a second group from the groups and resets the timer when the expiration time of the first group expires,
• wherein when the processor effort index of the first group is less than a threshold, a clock frequency of the processor is lowered before the expiration time expires.