Abstract: In an example, a method of processing commands for a non-volatile storage device includes storing the commands among a plurality of first-level queues in a random access memory (RAM). Each command is assigned to a first-level queue based on membership in one of a plurality of first-level categories. The method further includes removing selected commands from the plurality of first-level queues according to a first schedule and performing at least one operation on the selected commands. The method further includes storing the selected commands among a plurality of second-level queues in the RAM. Each selected command is assigned to a second-level queue based on whether the command is a read command or a write command. The method further includes removing active commands from the plurality of second-level queues according to a second schedule. The method further includes issuing the active commands to a back end of the controller for processing.

Abstract: A method of managing memory descriptors for a plurality of commands to a non-volatile semiconductor storage device includes requesting memory descriptors from a host system for each of the plurality of commands stored in a first memory, storing the memory descriptors for each of the plurality of commands in free descriptor regions of a plurality of descriptor regions in a second memory of the non-volatile semiconductor storage device, and maintaining a dynamic descriptor list in the second memory for each of the plurality of commands, the dynamic descriptor list for each of the plurality of commands comprising occupied descriptor regions of the plurality of descriptor regions in the second memory having associated memory descriptors. At least one of the occupied descriptor regions includes multiple memory descriptors and a single pointer to a next occupied descriptor region of the plurality of descriptor regions.

Abstract: A method of managing memory descriptors for a plurality of commands to a non-volatile semiconductor storage device includes requesting memory descriptors from a host system for each of the plurality of commands stored in a first memory, storing the memory descriptors for each of the plurality of commands in free descriptor regions of a plurality of descriptor regions in a second memory of the non-volatile semiconductor storage device, and maintaining a dynamic descriptor list in the second memory for each of the plurality of commands, the dynamic descriptor list for each of the plurality of commands comprising occupied descriptor regions of the plurality of descriptor regions in the second memory having associated memory descriptors. At least one of the occupied descriptor regions includes multiple memory descriptors and a single pointer to a next occupied descriptor region of the plurality of descriptor regions.

Abstract: In an example, a method of managing direct memory access (DMA) descriptors for commands to a non-volatile semiconductor storage device includes requesting DMA descriptors from the host system for each of a plurality of the commands stored in a command random access memory (RAM). The method further includes storing the DMA descriptors for each of the plurality of the commands in free descriptor regions in a descriptor RAM. The method further includes maintaining a dynamic descriptor list in the descriptor RAM for each of the plurality of commands, the dynamic descriptor list for each of the plurality of commands comprising occupied descriptor regions in the descriptor RAM having associated DMA descriptors.

Abstract: In an example, a method of fetching direct memory access (DMA) descriptors for commands to a non-volatile semiconductor storage device includes storing the commands among a plurality of queues in a command random access memory (RAM). The method further includes processing one or more of the commands from the plurality of queues and issuing requests to read from or write into the non-volatile semiconductor storage device according to the processing. The method further includes fetching DMA descriptors from the host system for the processed commands according to a real-time fetch quota. The method further includes pre-fetching DMA descriptors from the host system for queued commands that are not being processed according to a pre-fetch quota. The method further includes storing fetched and pre-fetched DMA descriptors in a descriptor RAM.

Abstract: In an example, a method of managing direct memory access (DMA) descriptors for commands to a non-volatile semiconductor storage device includes requesting DMA descriptors from the host system for each of a plurality of the commands stored in a command random access memory (RAM). The method further includes storing the DMA descriptors for each of the plurality of the commands in free descriptor regions in a descriptor RAM. The method further includes maintaining a dynamic descriptor list in the descriptor RAM for each of the plurality of commands, the dynamic descriptor list for each of the plurality of commands comprising occupied descriptor regions in the descriptor RAM having associated DMA descriptors.

Abstract: In an example, a method of fetching direct memory access (DMA) descriptors for commands to a non-volatile semiconductor storage device includes storing the commands among a plurality of queues in a command random access memory (RAM). The method further includes processing one or more of the commands from the plurality of queues and issuing requests to read from or write into the non-volatile semiconductor storage device according to the processing. The method further includes fetching DMA descriptors from the host system for the processed commands according to a real-time fetch quota. The method further includes pre-fetching DMA descriptors from the host system for queued commands that are not being processed according to a pre-fetch quota. The method further includes storing fetched and pre-fetched DMA descriptors in a descriptor RAM.

Abstract: In an example, a method of processing commands for a non-volatile storage device includes storing the commands among a plurality of first-level queues in a random access memory (RAM). Each command is assigned to a first-level queue based on membership in one of a plurality of first-level categories. The method further includes removing selected commands from the plurality of first-level queues according to a first schedule and performing at least one operation on the selected commands. The method further includes storing the selected commands among a plurality of second-level queues in the RAM. Each selected command is assigned to a second-level queue based on whether the command is a read command or a write command. The method further includes removing active commands from the plurality of second-level queues according to a second schedule. The method further includes issuing the active commands to a back end of the controller for processing.