Copyback optimization for memory system

• US 8,185,706 B2
• Filed: 08/18/2008
• Issued: 05/22/2012
• Est. Priority Date: 04/30/2008
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Wakrat, Nir Jacob, Helm, Mark Alan
• Primary Examiner(s): DOAN, DUC T
• Application Number:
  US12/193,638
• Publication Number:
  US 20090276560A1
• Time in Patent Office: 1,373 Days
• Field of Search: None
• US Class Current: 711/154
• 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;

storing the data page in a register;

determining when the data page stored in the register has changed including reading a data change indicator associated with the data page;

when the data change indicator indicates that the data page has changed, sending the data page to a controller for processing including;

determining an error-related parameter associated with the data page,

correcting, by the controller, the error-related parameter, and

storing the data page and the corrected error-related parameter in the register; and

when the data change indicator indicates that the data page stored in the register is unchanged, sending metadata associated with the data page to the controller for processing including;

generating an error-related parameter associated with the metadata, and

storing the generated error-related parameter associated with the metadata in the register; and

writing contents in the register including the generated error-related parameter associated with the metadata stored in the register to a new data page in the non-volatile memory.

2. The method of claim 1, where the reading the data change indicator includes reading data associated with an error detection code.

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

computing a data change indicator associated with the data page; and

determining if the data page has changed including reading the computed data change indicator.

4. The method of claim 1, further comprising;

correcting the error-related parameter associated with the metadata associated with the data page prior to storing the data page and the corrected error-related parameter associated with the metadata in the register.

5. The method of claim 1, further comprising determining a new data change indicator based on the data page and the corrected error-related parameter stored in the register.

6. 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 to perform one or more functions comprising;

obtaining a data page from the non-volatile memory;

storing the data page in a register;

determining when the data page stored in the register has changed including reading a data change indicator associated with the data page;

when the data change indicator indicates that the data page has changed, sending the data page through the interface to a controller for processing including;

determining an error-related parameter associated with the data page,

correcting, by the controller, the error-related parameter, and

storing the data page and the corrected error-related parameter in the register; and

when the data change indicator indicates that the data page stored in the register is unchanged, sending metadata associated with the data page to the controller for processing including;

generating an error-related parameter associated with the metadata, and

storing the generated error-related parameter associated with the metadata in the register; and

writing contents in the register including the generated error-related parameter associated with the metadata stored in the register to a new data page in the non-volatile memory.

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

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

computing the data change indicator associated with the data page; and

determining when the data page has changed including reading the computer data change indicator.

9. The system of claim 6, where the processor is operable to perform one or more functions comprising:

when the data change indicator indicates that the data page stored in the register is unchanged, sending metadata associated with the data page to the controller for processing including;

determining an error-related parameter associated with the metadata, and

storing the data page and the error-related parameter associated with the metadata in the register; and

writing contents in the register including the data page and the error-related parameter associated with the metadata stored in the register to a new data page in the non-volatile memory.

10. 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 to the controller for processing;

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

determining whether the processed data page has changed;

when it is determined that the processed data page has changed;

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

writing contents in the register to the non-volatile memory;

or

when it is determined that the processed data page has not changed;

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

writing contents in the register to the non-volatile memory.

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

reading a data change indicator for the processed data page.

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

13. The method of claim 10, 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.

14. 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 through the interface to the controller for processing;

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

determining whether the processed data page has changed;

when it is determined that the processed data page has changed;

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

writing contents in the register to the non-volatile memory;

or

when it is determined that the processed data page has not changed;

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

writing contents in the register to the non-volatile memory.

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

reading a data change indicator for the processed data page.

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

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

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

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