Copyback Optimization for Memory System

• US 20090276560A1
• Filed: 08/18/2008
• Published: 11/05/2009
• Est. Priority Date: 04/30/2008
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Wakrat, Nir Jacob, Helm, Mark Alan
• Granted Patent: US 8,185,706 B2
• Time in Patent Office: Days
• US Class Current: 711/101
• CPC Class Codes: G06F 11/1068 in sector programmable memories, e.g. flash disk G06F11/1072 takes precedence

Abstract

In a copyback or read operation for a non-volatile memory subsystem, data page change indicators are used to manage transfers of data pages between a register in non-volatile memory and a controller that is external to the non-volatile memory.

Claims

1. A method comprising:

obtaining a data page from non-volatile memory of a memory subsystem;

determining if the data page has changed; and

if the data page has changed,

sending the data page to a controller for processing;

if the data page is unchanged,

sending metadata associated with the data page to the controller for processing.

2. The method of claim 1, where determining if the data page has changed, further comprises:

reading a data change indicator for the data page.

3. The method of claim 2, where the data change indicator is associated with an error detection code.

4. The method of claim 1, where determining if the data page has changed, further comprises:

computing a data change indicator for the data page; and

determining if the data page has changed based on the data change indicator.

5. A system comprising:

an interface adapted for coupling to a controller;

non-volatile memory;

a processor coupled to the non-volatile memory and the interface, the processor operable for obtaining a data page from the non-volatile memory;

determining if the data page has changed; and

if the data page has changed,

sending the data page through the interface to the controller for processing;

if the data page has not changed,

sending metadata associated with the data page through the interface to the controller for processing.

6. The system of claim 5, where determining if the data page has changed, further comprises:

reading a data change indicator for the data page.

7. The system of claim 6, where the data change indicator is associated with an error detection code.

8. The system of claim 5, where determining if the data page has changed, further comprises:

computing a data change indicator for the data page; and

determining if the data page has changed based on the data change indicator.

9. A method comprising:

obtaining a data page and associated metadata from non-volatile memory of a memory subsystem coupled to a controller;

storing the data page in a register of the memory subsystem;

sending the data page and associated metadata from the register to the controller for processing;

receiving a processed data page and associated metadata from the controller;

determining if the processed data page has changed;

if the processed data page has changed,

writing the processed data page and associated metadata to the register in the memory subsystem;

if the processed data page has not changed,

writing the associated metadata to the register in the memory subsystem; and

writing the register contents to the non-volatile memory.

10. The method of claim 9, where determining if the processed data page has changed, further comprises:

reading a data change indicator for the processed data page.

11. The method of claim 10, where the data change indicator is associated with an error detection code.

12. The method of claim 9, where determining if the processed data page has changed, further comprises:

computing a data change indicator for the processed data page; and

determining if the processed data page has changed based on the data change indicator.

13. A system comprising:

an interface adapted for coupling to a controller;

non-volatile memory;

a processor coupled to the non-volatile memory and the interface, the processor operable for obtaining a data page and associated metadata from non-volatile memory of a memory subsystem coupled to the controller;

storing the data page in a register of the memory system;

sending the data page and associated metadata from the register through the interface to the controller for processing;

receiving a processed data page and associated metadata from the controller through the interface;

determining if the processed data page has changed;

if the processed data page has changed,

transferring the processed data page and associated metadata to the register in the memory subsystem;

if the processed data page has not changed,

transferring the processed metadata to the register in the memory subsystem; and

writing the register contents to the non-volatile memory.

14. The system of claim 13, where determining if the processed data page has changed, further comprises:

reading a data change indicator for the processed data page.

15. The system of claim 14, where the data change indicator is associated with an error detection code.

16. The system of claim 13, where determining if the processed data page has changed, further comprises:

computing a data change indicator for the processed data page; and

determining if the processed data page has changed based on the data change indicator.

17. A system comprising:

means for obtaining a data page from non-volatile memory of a memory subsystem;

means for determining if the data page has changed; and

if the data page has changed,

means for sending the data page to a controller for processing;

if the data page is unchanged,

means for sending metadata associated with the data page to the controller for processing.