Method for enhancing life cycle of memory

• US 8,140,737 B2
• Filed: 01/30/2007
• Issued: 03/20/2012
• Est. Priority Date: 01/30/2007
• Status: Active Grant

• Current Assignee: Skymedi Corporation
• Original Assignee: Skymedi Corporation
• Inventors: Shone, Fuja, Tai, Shih-Chieh
• Primary Examiner(s): Bragdon, Reginald
• Assistant Examiner(s): MACKALL, LARRY T
• Application Number:
  US11/668,469
• Publication Number:
  US 20080183947A1
• Time in Patent Office: 1,876 Days
• Field of Search: 711/103
• US Class Current: 711/103
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 2212/1036 Life time enhancement
• CPC Class Codes: G06F 2212/7211 Wear leveling

Abstract

A hierarchical mechanism for preventing concentrated wear on single physical block or a specific set of physical blocks in the physical memory is proposed. The logical blocks mapping to the physical blocks in the physical memory are classified into two different levels for implicitly representing the modification times of the physical blocks. A modify count and a maximum modify count are further included for counting the modification times in a single process of the hierarchical mechanism and for limiting the modification times in single process, leading to the probabilities of all the physical blocks being modified in the physical memory being balanced. The breakdown of the physical memory caused by the breakdown of a specific set of physical blocks or single physical block is thus prevented.

Claims

1. A method for enhancing a life cycle of memory comprising:

after all logical data blocks of the memory are at a first level, updating a content of a logical data block and moving the content of the logical data block from a first physical block of the memory to a free physical data block of the memory;

updating a level of the logical data block from the first level to a second level and updating a modify count of the memory in response to the movement from the first physical block to the free physical data block when the modify count has not reached a predetermined value, wherein the second level indicates at least one more modification on the logical data block than the first level, and the modify count of the memory indicates a sum of modifications on all the logical data blocks of the memory between a transition from the first level and the second level of all the logical data blocks of the memory;

when the modify count reaches the predetermined value, updating the level of only remaining logical data blocks which have not been modified between the transition from the first level to the second level and moving contents stored in physical blocks corresponding to the remaining logical data blocks to current free physical data blocks of the memory without updating the contents of the remaining logical data blocks; and

when all the logical data blocks of the memory reach the second level, resetting the modify count.

2. The method of claim 1 wherein updating the level of only the remaining logical data blocks comprises continuing updating the level of the remaining logical data blocks until the second level is reached for all the logical data blocks of the memory.

3. The method of claim 1 wherein updating the level of the logical data block from the first level to the second level and updating the modify count of the memory in response to the movement from the first physical data block to the free physical data block when the modify count has not reached the predetermined value comprises continuing increasing the level of all the logical data blocks of the memory until the second level is reached for all the logical data blocks of the memory and increasing the modify count of the memory in response to the movement from each physical data block to each current free physical data block when the modify count is smaller than the predetermined value.

4. The method of claim 1 wherein updating the content of the logical data block and moving the content of the logical data block from the first physical block of the memory to the free physical data block of the memory comprises:

modifying a content in a logical data block to generate a modified logical data block;

associating a free physical data block, to which the contents of the logical data block will be moved, with the modified logical data block;

storing the modified content in the associated free physical data block; and

if the modify count is greater than a predetermined value, moving a content of a physical data block of the memory associated with an unmodified logical block to a current free physical data block of the memory.