Caching performance optimization

• US 8,291,166 B2
• Filed: 05/24/2010
• Issued: 10/16/2012
• Est. Priority Date: 01/20/2006
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Cornwell, Michael J., Dudte, Christopher P., Herman, Kenneth L.
• Primary Examiner(s): TSAI, SHENG JEN
• Application Number:
  US12/786,115
• Publication Number:
  US 20100228909A1
• Time in Patent Office: 876 Days
• Field of Search: 711/118, 711/103, 711/E12.001, 711/E12.008, 711/E12.041
• US Class Current: 711/118
• CPC Class Codes: G06F 12/0888 using selective caching, e.g. bypass

Abstract

A method for managing data storage is described. The method includes receiving data from an external host at a peripheral storage device, detecting a file system type of the external host, and adapting a caching policy for transmitting the data to a memory accessible by the storage device, wherein the caching policy is based on the detected file system type. The detection of the file system type can be based on the received data. The detection bases can include a size of the received data. In some implementations, the detection of the file system type can be based on accessing the memory for file system type indicators that are associated with a unique file system type. Adapting the caching policy can reduce a number of data transmissions to the memory. The detected file system type can be a file allocation table (FAT) system type.

Claims

1. A method for managing data, the method comprising:

receiving at a peripheral storage device an indication to prepare to perform memory operations on non-volatile memory of the peripheral storage device, wherein the received indication corresponds to the peripheral storage device being communicatively connected to an external host system;

in response to receiving the indication and before receiving a command to perform the memory operations, identifying data stored in the non-volatile memory of the peripheral storage device that is likely to be frequently accessed while performing the memory operations;

caching the identified data in a cache of the peripheral storage device;

while performing the memory operations, modifying at least a portion of the identified data in the cache without rewriting the modified portion of the identified data in the cache to the non-volatile memory; and

writing at least the modified portion of the identified data from the cache to the non-volatile memory after performing the memory operations.

2. The method of claim 1, wherein the identified data that is likely to be frequently accessed includes file structure data for a file system used to store files in the non-volatile memory.

3. The method of claim 2, wherein the file structure data includes a file access table (FAT).

4. The method of claim 1, wherein the identified data that is likely to be frequently accessed includes directory entries for a file system used to store files in the non-volatile memory.

5. The method of claim 1, wherein the non-volatile memory includes flash memory.

6. The method of claim 1, wherein the modified portion of the identified data is written from the cache to the non-volatile memory in response to the peripheral storage device being disconnected from the external host system.

7. The method of claim 1, wherein the modified portion of the identified data is written from the cache to the non-volatile memory in response to a power source for the peripheral storage device changing from a power source external to the peripheral storage device to a portable power source local to the peripheral storage device.

8. The method of claim 1, wherein the modified portion of the identified data is written from the cache to the non-volatile memory in response to a power source for the peripheral storage device changing from a portable power source local to the peripheral storage device to a power source external to the peripheral storage device.

9. The method of claim 1, wherein writing at least the modified portion of the identified data from the cache to the non-volatile memory causes a corresponding portion of data stored in the memory to be updated to reflect modifications made to the identified data while performing the memory operations.

10. The method of claim 1, wherein the non-volatile memory of the peripheral storage device includes units of non-volatile memory, each of which includes multiple sub-units of non-volatile memory;

wherein the peripheral storage device is configured to write data to the non-volatile memory in units of non-volatile memory;

wherein the portion of the identified data modified in the cache comprises a sub-unit of non-volatile memory; and

wherein writing at least the modified portion of the identified data from the cache to the non-volatile memory includes writing a unit of non-volatile memory that includes the modified portion of the identified data from the cache to the non-volatile memory.

11. The method of claim 10, wherein modifying at least the portion of the identified data in the cache includes performing multiple write operations to one or more storage locations in the cache that are associated with the identified data.

12. The method of claim 10, wherein the units of non-volatile memory include blocks of non-volatile memory and the sub-units of non-volatile memory include pages of non-volatile memory.

20. The method of claim 1, wherein the data that is likely to be frequently accessed is identified based on a file type associated with the data or a location in the non-volatile memory at which the data is stored.

13. An article of manufacture comprising machine-readable instructions operable to cause a data processing apparatus to:

receive an indication to prepare to perform memory operations on non-volatile memory of the article of manufacture, wherein the received indication corresponds to the article of manufacture being communicatively connected to an external host system;

in response to receiving the indication and before receiving a command to perform the memory operations, identifying data stored in the non-volatile memory that is likely to be frequently accessed while performing the memory operations;

caching the identified data in a cache of the article of manufacture;

while performing the memory operations, modifying at least a portion of the identified data in the cache without rewriting the modified portion of the identified data in the cache to the non-volatile memory; and

writing at least the modified portion of the identified data from the cache to the non-volatile memory after performing the memory operations.

14. The article of manufacture of claim 13, wherein the identified data that is likely to be frequently accessed includes file structure data for a file system used to store files in the non-volatile memory.

15. The article of manufacture of claim 13, wherein the identified data that is likely to be frequently accessed includes directory entries for a file system used to store files in the non-volatile memory.

16. The article of manufacture of claim 13, wherein the modified portion of the identified data is written from the cache to the non-volatile memory in response to the article of manufacture being disconnected from the external host system.

17. A system for managing data comprising:

non-volatile memory configured to store data and to provide access to stored data;

an interface configured to receive an indication to prepare to perform memory operations on the non-volatile memory, wherein the received indication corresponds to the system being communicatively connected to an external host system;

a cache configured to cache data for use during the memory operations; and

a controller configured to;

in response to the indication and before receiving a command to perform the memory operations, to prepare to perform the memory operations, identify data stored in the non-volatile memory that is likely to be frequently accessed while performing the memory operations;

cache the identified data in the cache;

while performing the memory operations, modify at least a portion of the identified data in the cache without rewriting the modified portion of the identified data in the cache to the non-volatile memory; and

writing at least the modified portion of the identified data from the cache to the non-volatile memory after performing the memory operations.

18. The system of claim 17, wherein the identified data that is likely to be frequently accessed includes file structure data for a file system used to store files in the non-volatile memory.

19. The system of claim 17, wherein the identified data that is likely to be frequently accessed includes directory entries for a file system used to store files in the non-volatile memory.