Host read command return reordering based on time estimation of flash read command completion

摘要

Managing data returns to a host in response to read commands, an operation monitor of a solid-state drive (SSD) manages counters used to hold metrics that characterize the estimated time to complete a read operation on a corresponding flash die. A timer generates a periodic event which decrements the counters over time. The value stored in each counter is generated for flash operations submitted to the corresponding die and is, generally, based on the operational history and the physical location of the operation. Whenever a read command is scheduled for submission to a particular die, the time estimate for that particular read operation is retrieved and, based on this information, the optimum order in which to return data to the host is determined. This order is used to schedule and program data transfers to the host so that a minimum number of read commands get blocked by other read commands.

主权项

1. A method for managing returns to a host in response to read commands received by a solid-state drive (SSD) device from said host, the method comprising:
receiving a data read command from said host; computing the total estimated time to completion of said read command based on an estimated time to completion for each operation submitted to a respective non-volatile memory die corresponding to said read command; determining, based on said total estimated time to completion of said read command, in what order to return requested data to said host relative to other data read commands received from said host; and returning said requested data to said host in the order determined.