Methods of detecting fast reuse memory blocks and memory block management methods using the same

• US 10,048,892 B2
• Filed: 02/10/2017
• Issued: 08/14/2018
• Est. Priority Date: 06/01/2016
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Moon, Sang-kwon, Lee, Jong-youl, Ahn, Seong-jun, Lee, Hee-won
• Primary Examiner(s): Ojha, Ajay
• Application Number:
  US15/429,496
• Publication Number:
  US 20170351459A1
• Time in Patent Office: 550 Days
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 2212/7201 Logical to physical mapping or translation of blocks or pages
• CPC Class Codes: G06F 2212/7205 Cleaning, compaction, garbage collection, erase control
• CPC Class Codes: G06F 3/0608 Saving storage space on storage systems
• CPC Class Codes: G06F 3/0616 in relation to life time, e.g. increasing Mean Time Between Failures [MTBF]
• CPC Class Codes: G06F 3/064 Management of blocks
• CPC Class Codes: G06F 3/0652 Erasing, e.g. deleting, data cleaning, moving of data to a wastebasket
• CPC Class Codes: G06F 3/0679 Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]

Abstract

Fast reuse memory block detection methods and memory block management methods using the same are provided. A fast reuse memory block detection method may include selecting a memory block from memory blocks included in a nonvolatile memory device as a reference block at an initially set period, managing one of an erase time and a program time of the reference block, and determining whether other memory blocks are fast reuse memory blocks, based on a use period that is determined according to the managed one of the erase time and the program time of the reference block.

Claims

1. A method of detecting a fast reuse memory block, the method comprising:

selecting a memory block from memory blocks included in a nonvolatile memory device as a reference block at an initially set period;

managing one of an erase time and a program time of the reference block, wherein the one of the erase time and the program time of the reference block is one of a calculated difference in time between a first time that the reference block is erased and a second time that the reference block is erased and a calculated difference in time between a first time that the reference block is programmed and a second time that the reference block is programmed; and

determining, based on a use period that is determined according to the managed one of the erase time and the program time of the reference block, whether other memory blocks are fast reuse memory blocks.

2. The method of claim 1, wherein the reference block is selected from memory blocks that are changed to active blocks from among memory blocks that were included in a free block list at the initially set period.

3. The method of claim 2, wherein the memory blocks in the free block list are changed to the active blocks based on an order in which the memory blocks were registered in the free block list as free blocks, and wherein the reference block is selected from the memory blocks that were changed to the active blocks at the initially set period.

4. The method of claim 1, wherein a plurality of reference blocks are selected for respective periods that are different from each other.

5. The method of claim 1, wherein the managing comprises:

marking the managed one of the erase time and the program time of the reference block;

calculating one of an erase cycle and a program cycle of the reference block based on the marked one of the erase time and the program time;

determining that the calculated one of the erase cycle and the program cycle is less than or equal to an initially set threshold value; and

determining the reference block as a fast reuse memory block based on the determination that the calculated one of the erase cycle and the program cycle of the reference block is less than or equal to the initially set threshold value.

6. The method of claim 5,

wherein the marked one of the erase time and the program time is a marked erase time,

wherein the calculated one of the erase cycle and the program cycle is a calculated erase cycle, and

wherein the calculating comprises:

detecting a detected erase time when the reference block is erased after again being selected as an active block; and

calculating the calculated erase cycle by computing a difference between the detected erase time and the marked erase time.

7. The method of claim 5, further comprising:

fixing, based on the reference block being determined as a fast reuse memory block, the selected memory block as the reference block such that the reference block is not changed to a new memory block.

8. The method of claim 5, further comprising determining, based on the reference block being determined as a fast reuse memory block, a fast reuse count of the reference block by adding a value of “

1”

to a value that is obtained by dividing a time of a period, within which the reference block is selected, by an erase cycle time of the reference block.

9. The method of claim 5,

wherein the calculated one of the erase cycle and the program cycle is a calculated erase cycle, and

wherein the determining whether other memory blocks are fast reuse memory blocks comprises:

determining, based on the calculated erase cycle of the reference block, whether memory blocks that are used as active blocks during an erase interval of the reference block are fast reuse memory blocks.

10. The method of claim 1, wherein determining whether other memory blocks are fast reuse memory blocks comprises determining, based on the managed one of the erase time and the program time of the reference block, memory blocks that are used as active blocks during a section where the reference block is detected as a fast reuse memory block as fast reuse memory blocks.

11. The method of claim 1, further comprising:

registering information in a fast reuse block table about memory blocks that are respectively determined as fast reuse memory blocks,

wherein the fast reuse block table comprises respective information about at least a block address and a fast reuse count for the memory blocks that are respectively determined as fast reuse memory blocks.

19. The method of claim 1, wherein the determining whether other memory blocks are fast reuse memory blocks comprises:

determining that the reference block is a fast reuse memory block based on the one of the erase time and the program time being less than or equal to an initially set threshold value;

registering the reference block in a fast reuse block table; and

registering the other memory blocks in the fast reuse block table with a fast reuse count that is equal to a fast reuse count of the reference block.

12. A memory block management method, the method comprising:

detecting fast reuse memory blocks, in each of which one of an erase cycle and a program cycle is less than or equal to an initially set first threshold value, from among a plurality of memory blocks included in a nonvolatile memory device;

determining a memory block, of which a fast reuse count is greater than or equal to an initially set second threshold value, from among the detected fast reuse memory blocks as a wear leveling block; and

performing wear leveling processing on the wear leveling block,

wherein the detecting the fast reuse memory blocks comprises;

selecting a memory block from the plurality of memory blocks in the nonvolatile memory device as a reference block at an initially set period;

managing one of an erase time and a program time of the reference block, wherein the one of the erase time and the program time of the reference block is one of a calculated difference in time between a first time that the reference block is erased and a second time that the reference block is erased and a calculated difference in time between a first time that the reference block is programmed and a second time that the reference block is programmed; and

determining, based on a use period that is determined according to the one of the erase time and the program time of the reference block, whether other memory blocks are fast reuse memory blocks.

13. The method of claim 12, wherein the determination of whether the other memory blocks are fast reuse memory blocks comprises:

determining, based on the managed one of the erase time and the program time of the reference block, memory blocks that are used as active blocks during a section where the reference block is detected as a fast reuse memory block as fast reuse memory blocks.

14. The method of claim 12, wherein the performing the wear leveling processing on the wear leveling block comprises:

selecting, from among memory blocks that are included in a data block list, a memory block having an update count that is less than a reference value; and

copying data from the selected memory block to the memory block determined as the wear leveling block.

15. A memory block management method, the method comprising:

selecting a memory block, from among memory blocks included in a nonvolatile memory device, as a reference block;

increasing a fast reuse count of the selected reference block based on a determination that a use period of the selected reference block is less than a first threshold, the use period being a time between adjacent erase or program operations that are performed on the selected reference block;

setting a fast reuse count that is equal to the increased fast reuse count of the selected reference block for active memory blocks that are used within the use period of the selected reference block; and

performing wear leveling processing on one or more of the memory blocks based on a determination that a respective fast reuse count of the one or more of the memory blocks is greater than a second threshold,

wherein the performing the wear leveling processing comprises copying data to the one or more of the memory blocks comprising the fast reuse counts that are greater than the second threshold from one or more respective memory blocks that have an update count that is less than a third threshold.

16. The memory block management method of claim 15, wherein the selecting the memory block as a reference block comprises selecting a memory block that is erased based on a change of the memory block from a free block to an active block.

17. The memory block management method of claim 16, wherein the selecting the memory block as a reference block is based on a determination that a previously selected reference block has not been reused within a predetermined period of time.

18. The memory block management method of claim 15, wherein the use period of the selected reference block is a time between adjacent erase operations that are performed on the reference block.