Method and system for communicating with non-volatile memory

• US 9,430,411 B2
• Filed: 11/13/2013
• Issued: 08/30/2016
• Est. Priority Date: 11/13/2013
• Status: Active Grant

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Inventors: Lin, Gary, Davidson, Matt, Barrocas, Milton, Gutta, Aruna
• Primary Examiner(s): Farrokh, Hashem
• Application Number:
  US14/079,433
• Publication Number:
  US 20150134884A1
• Time in Patent Office: 1,021 Days
• US Class Current: 1/1
• CPC Class Codes: G06F 12/00 Accessing, addressing or allocating within memory systems or architectures digital input from, or digital output to record carriers, e.g. to disk storage units, G06F3/06
• CPC Class Codes: G06F 13/00 Interconnection of, or transfer of information or other signals between, memories, input/output devices or central processing units interface circuits for specific input/output devices G06F3/00 ; multiprogram control therefor G06F9/46; multiprocessor systems G06F15/16
• CPC Class Codes: G06F 13/18 based on priority control G06F13/1605 takes precedence
• CPC Class Codes: G06F 2212/7208 Multiple device management, e.g. distributing data over multiple flash devices
• CPC Class Codes: G06F 3/0688 Non-volatile semiconductor memory arrays

Abstract

Apparatus and methods implemented therein are disclosed for communicating with flash memories. The apparatus comprises a flash interface module and a processor in communication with the flash interface module. The flash interface module is configured for communication with a first and second flash bank. The processor is configured to generate a plurality of command sequences in response to receiving a plurality of flash commands from a host system. Each of the plurality of command sequences corresponds to a respective one of the plurality of flash commands. Some of the plurality of command sequences comprises a first portion and a second portion and each of the first portion and second portion are atomic. The processor associates each of the plurality of command sequences with a priority, and via the flash interface module, selects one of the plurality of the command sequences based on the priority associated with the one of the plurality of the command sequences and transmits sequentially the first portion of the one of the plurality of the command sequences to either one of the first flash bank or the second flash bank.

Claims

1. A method for managing communication in a flash memory system, the flash memory system comprising a memory controller, a first flash bank and a second flash bank, the first and second flash banks communicatively coupled to the memory controller via a common flash interface, the method comprising the memory controller:

receiving a first flash command and a second flash command from a host system;

generating from the first flash command, a first command sequence wherein the first command sequence comprises a first atomic portion and a second atomic portion and generating from the second flash command, a second command sequence wherein the second command sequences comprises at least one atomic portion;

attaching a first identifier to each of the first and second portion of the first command sequence identifying the first flash bank, and a second identifier to the at least one portion of the second command sequence identifying the second flash bank;

selecting the first command sequence based on a first criteria and a second criteria, wherein the first criteria is associated with the first command sequence and the second criteria is associated with the second command sequence;

communicating the first portion of the first command sequence to the first flash bank via the common flash interface;

after communicating the first portion, and prior to communicating the second portion of the first command sequence, communicating the at least one portion of the second command sequence to the second flash bank via the common flash interface; and

after communicating the at least one portion of the second command sequence, communicating the second portion of the first command sequence to the first flash bank via the common flash interface.

2. The method of claim 1, wherein the at least one portion of the second command sequence is communicated in response to detecting that the first portion of the first command sequence was communicated to the first flash bank.

3. The method of claim 2, wherein the second portion is communicated in response to detecting that the at least one portion of the second command sequence was communicated to the second flash bank.

4. The method of claim 1 wherein the first command sequence is associated with a first thread and the second command sequence is associated with a second thread and wherein the first thread is associated with the first flash bank and the second thread is associated with the second flash bank.

5. The method of claim 4 wherein the first criteria indicates a state of the first thread and the second criteria indicates a state of the second thread, and wherein selecting the first command sequence is based on determining that the state of the first thread is active and that the state of the second thread is inactive.

6. The method of claim 5 further comprises assigning the first thread a first priority and the second thread a second priority.

7. The method of claim 5 further comprises, in response to communicating the first portion, adjusting the first priority.

8. The method of claim 7 further comprises detecting, after communicating the first portion, the state of the second thread.

9. The method of claim 8, further comprises in response to detecting the second thread is active, comparing the second priority with the adjusted first priority.

10. The method of claim 9, wherein in response to determining that the second priority exceeds the adjusted first priority, communicating the at least one portion of the second command sequence to the second flash bank via the common flash interface.

11. The method of claim 1 wherein communicating the first portion and the second portion of the first command sequence comprises selecting the first flash bank and wherein communicating the at least one portion of the second command sequence comprises unselecting the first flash bank.

12. A method for communicating with a first flash bank and a second flash bank via a common flash interface, the method comprising a processor of a memory controller:

in response to receiving a first flash command from a host, determining that the first flash command is intended to be communicated to the first flash bank;

generating a command sequence from the first flash command, wherein the command sequence is associated with a first priority and comprises two portions, each portion comprising a series of commands, wherein the series of commands is atomic;

attaching to each portion identification information associated with the first flash bank;

communicating a first portion of the command sequence to the first flash bank in response to detecting the first priority;

in response to detecting a command in the series of commands in the first portion, generating an status indication, wherein the status indication indicates that the first portion of the command sequence has been communicated to the first flash bank;

receiving the indication and determining if another command sequence associated with a second priority and to be communicated to the second flash bank was received;

comparing the first priority with the second priority in response to determining that the another command sequence was received;

communicating the second portion of the command sequence to the first flash bank in response to the first priority being greater than the second priority; and

communicating the another command sequence to the second flash bank in response to the second priority being greater than the first priority.

14. The method of claim 12, wherein the first or second priority depends at least in part on a priority of a thread carrying the command sequence or the another command sequence.

15. The method of claim 12, wherein the first or second priority depends at least on both nature of the first command sequence or the another command sequence being a read or write of data and a priority of a thread carrying the command sequence of the another command sequence.

13. The method of 12 wherein the first or second priority depends at least in part on nature of the first command sequence or the another command sequence being a read or write of data.

16. A memory controller for communicating with a first flash bank and a second flash bank, the memory controller comprising:

a flash interface module configured for communication with the first and second flash banks; and

a processor in communication with the flash interface module, the processor configured to;

generate a plurality of command sequences in response to receiving a plurality of flash commands from a host system, wherein each of the plurality of command sequences corresponds to a respective one of the plurality of flash commands, wherein some of the plurality of command sequences comprise a first portion and a second portion and each of the first portion and second portion are atomic;

attach an identifier to each of the first and second portions identifying either the first or the second flash bank;

associate each of the plurality of command sequences with a priority; and

via the flash interface module, select one of the plurality of the command sequences based on the priority associated with the one of the plurality of the command sequences and transmit sequentially the first portion of the one of the plurality of the command sequences to either one of the first flash bank or the second flash bank.

17. The memory controller of claim 16 wherein the processor, via the flash interface module, is further configured to detect an end of the first portion of the one of the plurality of the command sequences.

18. The memory controller of claim 17 wherein the processor, via the flash interface module, is further configured to select a second one of the plurality of the command sequences in response to detecting the end of the first portion of the one of the plurality of the command sequences and wherein selecting the second one of the plurality of the command sequences is based on determining that a priority associated with the second one of the plurality of the command sequences is greater than the priority associated with the one of the plurality of the command sequences.

19. The memory controller of claim 18 wherein the processor, via the flash interface module, is further configured to transmit the first portion of the second one of the plurality of the command sequences to the other one of the first flash bank or the second flash bank.