Suspending and resuming non-volatile memory operations

• US 9,645,744 B2
• Filed: 01/16/2015
• Issued: 05/09/2017
• Est. Priority Date: 07/22/2014
• Status: Active Grant

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Inventors: Ellis, Robert W., Higgins, James M., Jones, Ryan R.
• Primary Examiner(s): LI, ZHUO H
• Application Number:
  US14/599,183
• Publication Number:
  US 20160026386A1
• Time in Patent Office: 844 Days
• CPC Class Codes: G06F 13/1642 with request queuing
• CPC Class Codes: G06F 3/061 Improving I/O performance
• CPC Class Codes: G06F 3/0659 Command handling arrangements, e.g. command buffers, queues, command scheduling
• CPC Class Codes: G06F 3/0679 Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]
• CPC Class Codes: G11C 16/32 Timing circuits

Abstract

A method of operation in a non-volatile memory system includes starting execution of a first memory operation from a first queue and in conjunction with starting a first timer, set to expire after a first predetermined time interval. The method further includes, in accordance with a determination that the first timer has expired, determining whether a second queue contains at least one memory operation for execution, and if so, suspending the first memory operation, executing a second memory operation from the second queue, and after completing execution of the second memory operation from the second queue, performing one or more subsequent operations (e.g., resuming execution of the first memory operation and restarting the first timer). In addition, the method includes, when the second queue does not contain at least one memory operation for execution, restarting the first timer, and continuing execution of the first memory operation from the first queue.

Claims

1. A method of operation in a non-volatile memory system, comprising:

starting, in the non-volatile memory system, execution of a first memory operation from a first queue;

in conjunction with starting execution of the first memory operation, starting a first timer in the non-volatile memory system, wherein the first timer is set to expire after a first predetermined time interval; and

after starting the first timer, in accordance with a determination that the first timer has expired, performing one or more operations in the non-volatile memory system including;

determining whether a second queue contains at least one memory operation for execution;

in accordance with a determination that the second queue contains at least one memory operation for execution, performing one or more operations including;

suspending the first memory operation from the first queue;

executing a second memory operation from the second queue; and

after completing execution of the second memory operation from the second queue, performing one or more subsequent operations; and

in accordance with a determination that the second queue does not contain at least one memory operation for execution, performing one or more operations including;

restarting the first timer, wherein restarting the first timer sets the first timer to expire after an interval equal to the first predetermined time interval; and

continuing execution of the first memory operation from the first queue.

2. The method of claim 1, wherein the one or more subsequent operations include:

restarting the first timer, wherein restarting the first timer sets the first timer to expire after an interval equal to the first predetermined time interval; and

resuming execution of the first memory operation from the first queue.

3. The method of claim 1, wherein read operations from a host system are placed in the second queue.

4. The method of claim 1, wherein:

the first queue and the second queue are logical queues; and

both the first queue and the second queue are part of a single physical queue.

5. The method of claim 1, wherein the first queue and the second queue are distinct physical queues.

6. The method of claim 1, wherein the non-volatile memory system includes a global indicator that, when set, indicates that memory operations in the first queue cannot be suspended, and the method further comprises:

setting the global indicator in accordance with a predefined condition or command;

in accordance with a determination that the global indicator is set, preventing suspension of memory operations in the first queue.

7. The method of claim 1, further comprising, in accordance with each of one or more subsequent determinations that the first timer has expired, performing one or more operations including:

determining whether the second queue contains at least one memory operation for execution;

in accordance with a determination that the second queue contains at least one memory operation for execution, performing one or more operations including;

suspending the first memory operation from the first queue;

executing a memory operation from the second queue; and

after completing execution of the memory operation from the second queue, performing one or more subsequent operations including;

restarting the first timer, wherein restarting the first timer sets the first timer to expire after an interval equal to the first predetermined time interval; and

resuming execution of the first memory operation from the first queue; and

in accordance with a determination that the second queue does not contain at least one memory operation for execution, performing one or more operations including;

restarting the first timer, wherein restarting the first timer sets the first timer to expire after an interval equal to the first predetermined time interval; and

continuing execution of the first memory operation from the first queue.

8. The method of claim 1, further comprising:

starting, in the non-volatile memory system, execution of a third memory operation from the first queue;

in conjunction with starting execution of the third memory operation, starting a second timer in the non-volatile memory system, wherein the second timer is set to expire after a second predetermined time interval; and

after starting the second timer, in accordance with a determination that the second timer has expired, performing one or more operations in the non-volatile memory system including;

determining whether the second queue contains at least one memory operation for execution;

in accordance with a determination that the second queue contains at least one memory operation for execution, performing one or more operations including;

suspending the third memory operation from the first queue;

executing a fourth memory operation from the second queue; and

after completing execution of the fourth memory operation from the second queue, performing one or more subsequent operations including;

restarting the second timer; and

resuming execution of the third memory operation from the first queue; and

in accordance with a determination that the second queue does not contain at least one memory operation for execution, performing one or more operations including;

restarting the second timer; and

continuing execution of the third memory operation from the first queue.

9. The method of claim 8, wherein the second predetermined time interval is distinct from the first predetermined time interval.

10. The method of claim 1, further comprising, in accordance with a determination that an indicator of a subsequent memory operation is set, preventing suspension of the subsequent memory operation.

11. The method of claim 1, wherein the non-volatile memory system includes a plurality of portions, a first queue, a second queue, and a portion-specific indicator that when set indicates that memory operations in the first queue cannot be suspended, wherein each portion includes one or more non-volatile memory devices;

and

the method further comprises, in accordance with a determination that the portion-specific indicator for a first portion of the non-volatile memory system is set, preventing suspension of memory operations in the first queue of the first portion of the non-volatile memory system.

12. A non-volatile memory system including a plurality of portions, each portion having one or more non-volatile memory devices, wherein for each portion, the non-volatile memory system comprises:

one or more timers;

a first queue and a second queue; and

a logic module, wherein the logic module is configured to;

start, in the non-volatile memory system, execution of a first memory operation from the first queue;

in conjunction with starting execution of the first memory operation, start a first timer of the one or more timers in the non-volatile memory system, wherein the first timer is set to expire after a first predetermined time interval; and

after starting the first timer, in accordance with a determination that the first timer has expired, perform one or more operations in the non-volatile memory system including;

determining whether the second queue contains at least one memory operation for execution;

in accordance with a determination that the second queue contains at least one memory operation for execution, performing one or more operations including;

suspending the first memory operation from the first queue;

executing a second memory operation from the second queue; and

after completing execution of the second memory operation from the second queue, performing one or more subsequent operations; and

in accordance with a determination that the second queue does not contain at least one memory operation for execution, performing one or more operations including;

restarting the first timer, wherein restarting the first timer sets the first timer to expire after an interval equal to the first predetermined time interval; and

continuing execution of the first memory operation from the first queue.

13. The non-volatile memory system of claim 12, wherein the one or more subsequent operations include:

restarting the first timer, wherein restarting the first timer sets the first timer to expire after an interval equal to the first predetermined time interval; and

resuming execution of the first memory operation from the first queue.

14. The non-volatile memory system of claim 12, wherein the non-volatile memory system includes a global indicator that, when set, indicates that memory operations in the first queue cannot be suspended, and the logic module is further configured to:

set the global indicator in accordance with a predefined condition or command;

in accordance with a determination that the global indicator is set, prevent suspension of memory operations in the first queue.

15. The non-volatile memory system of claim 12, the logic module further configured to, in accordance with each of one or more subsequent determinations that the first timer has expired, perform one or more operations including:

determining whether the second queue contains at least one memory operation for execution;

in accordance with a determination that the second queue contains at least one memory operation for execution, performing one or more operations including;

suspending the first memory operation from the first queue;

executing a memory operation from the second queue; and

after completing execution of the memory operation from the second queue, performing one or more subsequent operations including;

restarting the first timer, wherein restarting the first timer sets the first timer to expire after an interval equal to the first predetermined time interval; and

resuming execution of the first memory operation from the first queue; and

in accordance with a determination that the second queue does not contain at least one memory operation for execution, performing one or more operations including;

restarting the first timer, wherein restarting the first timer sets the first timer to expire after an interval equal to the first predetermined time interval; and

continuing execution of the first memory operation from the first queue.

16. The non-volatile memory system of claim 12, the logic module further configured to:

start, in the non-volatile memory system, execution of a third memory operation from the first queue;

in conjunction with starting execution of the third memory operation, start a second timer in the non-volatile memory system, wherein the second timer is set to expire after a second predetermined time interval; and

after starting the second timer, in accordance with a determination that the second timer has expired, perform one or more operations in the non-volatile memory system including;

determining whether the second queue contains at least one memory operation for execution;

in accordance with a determination that the second queue contains at least one memory operation for execution, performing one or more operations including;

suspending the third memory operation from the first queue;

executing a fourth memory operation from the second queue; and

after completing execution of the fourth memory operation from the second queue, performing one or more subsequent operations including;

restarting the second timer; and

resuming execution of the third memory operation from the first queue; and

in accordance with a determination that the second queue does not contain at least one memory operation for execution, performing one or more operations including;

restarting the second timer; and

continuing execution of the third memory operation from the first queue.

17. The non-volatile memory system of claim 12, the logic module further configured to, in accordance with a determination that an indicator of a subsequent memory operation is set, prevent suspension of the subsequent memory operation.

18. The non-volatile memory system of claim 12, wherein the non-volatile memory system includes a plurality of portions, a first queue, a second queue, and a portion-specific indicator that when set indicates that memory operations in the first queue cannot be suspended, wherein each portion includes one or more non-volatile memory devices;

and

the logic module is further configured to, in accordance with a determination that the portion-specific indicator for a first portion of the non-volatile memory system is set, prevent suspension of memory operations in the first queue of the first portion of the non-volatile memory system.

19. A non-transitory computer-readable storage medium storing one or more programs configured for execution by one or more processors of a non-volatile memory system, the one or more programs including instructions for:

starting, in the non-volatile memory system, execution of a first memory operation from a first queue;

in conjunction with starting execution of the first memory operation, starting a first timer in the non-volatile memory system, wherein the first timer is set to expire after a first predetermined time interval; and

after starting the first timer, in accordance with a determination that the first timer has expired, performing one or more operations in the non-volatile memory system including;

determining whether a second queue contains at least one memory operation for execution;

in accordance with a determination that the second queue contains at least one memory operation for execution, performing one or more operations including;

suspending the first memory operation from the first queue;

executing a second memory operation from the second queue; and

after completing execution of the second memory operation from the second queue, performing one or more subsequent operations; and

in accordance with a determination that the second queue does not contain at least one memory operation for execution, performing one or more operations including;

restarting the first timer, wherein restarting the first timer sets the first timer to expire after an interval equal to the first predetermined time interval and

continuing execution of the first memory operation from the first queue.

20. The non-transitory computer-readable storage medium of claim 19, wherein the one or more subsequent operations include:

restarting the first timer, wherein restarting the first timer sets the first timer to expire after an interval equal to the first predetermined time interval; and

resuming execution of the first memory operation from the first queue.

21. The non-transitory computer-readable storage medium of claim 19, wherein the non-volatile memory system includes a global indicator that, when set, indicates that memory operations in the first queue cannot be suspended, and the one or more programs further include instructions for:

setting the global indicator in accordance with a predefined condition or command;

in accordance with a determination that the global indicator is set, preventing suspension of memory operations in the first queue.

22. The non-transitory computer-readable storage medium of claim 19, the one or more programs further including instructions for, in accordance with each of one or more subsequent determinations that the first timer has expired, performing one or more operations including:

determining whether the second queue contains at least one memory operation for execution;

in accordance with a determination that the second queue contains at least one memory operation for execution, performing one or more operations including;

suspending the first memory operation from the first queue;

executing a memory operation from the second queue; and

after completing execution of the memory operation from the second queue, performing one or more subsequent operations including;

restarting the first timer, wherein restarting the first timer sets the first timer to expire after an interval equal to the first predetermined time interval; and

resuming execution of the first memory operation from the first queue; and

in accordance with a determination that the second queue does not contain at least one memory operation for execution, performing one or more operations including;

restarting the first timer, wherein restarting the first timer sets the first timer to expire after an interval equal to the first predetermined time interval; and

continuing execution of the first memory operation from the first queue.

23. The non-transitory computer-readable storage medium of claim 19, the one or more programs further including instructions for:

starting, in the non-volatile memory system, execution of a third memory operation from the first queue;

in conjunction with starting execution of the third memory operation, starting a second timer in the non-volatile memory system, wherein the second timer is set to expire after a second predetermined time interval; and

after starting the second timer, in accordance with a determination that the second timer has expired, performing one or more operations in the non-volatile memory system including;

determining whether the second queue contains at least one memory operation for execution;

in accordance with a determination that the second queue contains at least one memory operation for execution, performing one or more operations including;

suspending the third memory operation from the first queue;

executing a fourth memory operation from the second queue; and

after completing execution of the fourth memory operation from the second queue, performing one or more subsequent operations including;

restarting the second timer; and

resuming execution of the third memory operation from the first queue; and

in accordance with a determination that the second queue does not contain at least one memory operation for execution, performing one or more operations including;

restarting the second timer; and

continuing execution of the third memory operation from the first queue.

24. The non-transitory computer-readable storage medium of claim 19, the one or more programs further including instructions for, in accordance with a determination that an indicator of a subsequent memory operation is set, preventing suspension of the subsequent memory operation.

25. The non-transitory computer-readable storage medium of claim 19, wherein the non-volatile memory system includes a plurality of portions, a first queue, a second queue, and a portion-specific indicator that when set indicates that memory operations in the first queue cannot be suspended, wherein each portion includes one or more non-volatile memory devices;

and

the one or more programs further include instructions for, in accordance with a determination that the portion-specific indicator for a first portion of the non-volatile memory system is set, preventing suspension of memory operations in the first queue of the first portion of the non-volatile memory system.