Fairshare between multiple SSD submission queues

A method performed by a controller within a solid-state drive (SSD), the controller communicatively coupled to a non-volatile semiconductor memory device and comprising a first command queue and a second command queue, the method comprising:

• selecting from a submission queue of a plurality of submission queues at least one command from a host external to the solid state drive, the at least one command relating to an action to be performed on the non-volatile semiconductor memory device, the action comprising any one of the following types of action:
• reading from the memory device, writing to the memory device, and executing an internal command generated by the controller;
• determining if a size of data associated with in-flight commands received from the host via the submission queue of the plurality of submission queues and already present in at least one of the first command queue and second command queue exceeds a threshold, at least a portion of the in-flight commands already present in the first command queue relating to a same type of action to be performed on the non-volatile semiconductor memory device as that of the selected at least one command;
• adding the at least one command selected from the submission queue of the plurality of submission queues to the second command queue if the threshold is exceeded, otherwise adding the at least one command to the first command queue;
• and
• processing a first command from the first command queue and a second command from the second command queue to perform a first action and a second action, respectively, on the non-volatile semiconductor memory device, the first action being completed in advance of the second action.

A solid-state drive (SSD) comprising:

• a non-volatile semiconductor memory device;
• and
• a controller contained within the SSD, the SSD communicatively coupled to the non-volatile semiconductor memory device and configured to store data and retrieve data in the non-volatile semiconductor memory device in response to commands received from a host external to the solid-state drive, the controller comprising a first command queue and a second command queue, and configured to:
• select from a submission queue of a plurality of submission queues at least one command from the host, the at least one command relating to an action to be performed on the non-volatile semiconductor memory device, the action comprising any one of the following types of action:
• reading from the memory device, writing to the memory device, and executing an internal command generated by the controller,
• determine if either (i) a number of in-flight commands received from the host via the submission queue of the plurality of submission queues and already present in the first command queue, or (ii) a size of data associated with in-flight commands received from the host via the submission queue of the plurality of submission queues and already present in at least one of the first command queue and second command queue, exceeds a threshold, at least a portion of the in-flight commands already present in the first command queue relating to a same type of action to be performed on the non-volatile semiconductor memory device as that of the selected at least one command,
• add the at least one command selected from the submission queue of the plurality of submission queues to the second command queue if the threshold is exceeded, otherwise adding the at least one command to the first command queue, and
• process a first command from the first command queue and a second command from the second command queue to perform a first action and a second action, respectively, on the non-volatile semiconductor memory device, the first action being completed in advance of the second action.