Abstract: A method and apparatus to reduce read latency and improve read quality of service (Read QoS) for non-volatile memory, such as NAND array in a NAND device. For read commands that collide with an in-progress program array operation targeting the same program locations in a NAND array, the in-progress program is suspended and the controller allows the read command to read from the internal NAND buffer instead of waiting for the in-progress program to complete. For read commands queued during an in-progress program that is processing pre-reads in preparation for a program array operation, pre-read bypass allows the reads to be serviced between the pre-reads and before the program's array operation starts. In this manner, read commands can be serviced without suspending the in-progress program. Allowing internal NAND buffer reads and enabling pre-read bypass reduces read latency and improves Read QoS.

Abstract: A data structure is maintained for performing a program operation that is allowed to be suspended to perform reads in a NAND device, where the data structure indicates a plurality of tiers, where each tier of the plurality of tiers has a number of allowed suspends of the program operation while executing in the tier, and where a sum of the number of allowed suspends for all tiers of the plurality of tiers equals a maximum allowed number of suspends of the program operation. In response to performing a resume of the program operation, after performing a read following a suspend of the program operation, a determination is made of a tier of the plurality of tiers for the program operation and a subsequent suspend of the program operation is performed only after a measure of progress of the program operation has been exceeded in the determined tier.

Abstract: A method and apparatus to reduce read latency and improve read quality of service (Read QoS) for non-volatile memory, such as NAND array in a NAND device. For read commands that collide with an in-progress program array operation targeting the same program locations in a NAND array, the in-progress program is suspended and the controller allows the read command to read from the internal NAND buffer instead of waiting for the in-progress program to complete. For read commands queued during an in-progress program that is processing pre-reads in preparation for a program array operation, pre-read bypass allows the reads to be serviced between the pre-reads and before the program's array operation starts. In this manner, read commands can be serviced without suspending the in-progress program. Allowing internal NAND buffer reads and enabling pre-read bypass reduces read latency and improves Read QoS.

Abstract: A data structure is maintained for performing a program operation that is allowed to be suspended to perform reads in a NAND device, where the data structure indicates a plurality of tiers, where each tier of the plurality of tiers has a number of allowed suspends of the program operation while executing in the tier, and where a sum of the number of allowed suspends for all tiers of the plurality of tiers equals a maximum allowed number of suspends of the program operation. In response to performing a resume of the program operation, after performing a read following a suspend of the program operation, a determination is made of a tier of the plurality of tiers for the program operation and a subsequent suspend of the program operation is performed only after a measure of progress of the program operation has been exceeded in the determined tier.