Cache hints for computer file access

• US 20020116577A1
• Filed: 02/20/2001
• Published: 08/22/2002
• Est. Priority Date: 02/20/2001
• Status: Active Grant

• Current Assignee: McAfee, LLC
• Original Assignee: Networks Associates Technology, Inc. (McAfee, LLC)
• Inventors: Hursey, Neil John
• Granted Patent: US 6,721,847 B2
• Time in Patent Office: Days
• US Class Current: 711/118
• CPC Class Codes: G06F 12/0862 with prefetch
• CPC Class Codes: G06F 12/0866 for peripheral storage systems, e.g. disk cache
• CPC Class Codes: G06F 2212/6028 Prefetching based on hints or prefetch instructions
• CPC Class Codes: Y10S 707/99932 Access augmentation or optimizing
• CPC Class Codes: Y10S 707/99933 Query processing, i.e. searching
• CPC Class Codes: Y10S 707/99934 Query formulation, input preparation, or translation
• CPC Class Codes: Y10S 707/99953 Recoverability

Abstract

An application program (6) may issue a file access request to an operating system (4) accompanied by a caching hint. This caching hint may be selected in dependence upon the file type and file size of the computer file to which access has been requested. The data defining which hint type is to be used for each combination of file type and file size may be adaptively updated depending upon measured performance for the different hint types. The hint defining data may be initialised in dependence upon the operating system version and the installed memory size of the computer system concerned.

Claims

1. A computer program product comprising a computer program operable to control a computer to access a computer file, said computer program comprising:

(i) file characterising logic operable to detect at least one characteristic of said computer file;

(ii) cache hint selecting logic operable in dependence upon said at least one characteristic to select from among a plurality of different possible cache hints a selected cache hint to use in association with said access to said computer file; and

(iii) file access request issuing logic operable to issue to an operating system a file access request for said computer file accompanied by said selected cache hint.

2. A computer program product as claimed in claim 1, wherein said at least one characteristic includes at least one of:

(i) file type; and

(ii) file size.

3. A computer program product as claimed in claim 1, wherein said plurality of cache hints include at least one of:

(i) sequential access;

(ii) random access;

(iii) none; and

(iv) no hint.

4. A computer program product as claimed in claim 1, wherein said cache hint selecting logic is responsive to hint defining data that is adapted in use in dependence upon measured file access performance.

5. A computer program product as claimed in claim 4, wherein for each combination of said one or more characteristics of said computer file, said hint defining data stores data measuring file access performance for each of said plurality of different cache file hints.

6. A computer program product as claimed in claim 4, wherein said data measuring file access performance includes data defining a rate of data access achieved using each of said plurality of different cache hints.

7. A computer program product as claimed in claim 4, wherein said hint defining data is only update based upon performance measurements for a file determined not already to be cached.

8. A computer program as claimed in claim 4, wherein said hint defining data is initialised prior to measured performance data being available with data selected in dependence upon configuration characteristics of said computer.

9. A computer program product as claimed in claim 8, wherein said configuration characteristics include at least one of:

(i) operating system type; and

(ii) installed memory size.

10. A method of accessing a computer file, said method comprising the steps of:

(i) detecting at least one characteristic of said computer file;

(ii) selecting in dependence upon said at least one characteristic to select from among a plurality of different possible cache hints a selected cache hint to use in association with said access to said computer file; and

(iii) issuing to an operating system a file access request for said computer file accompanied by said selected cache hint.

11. A method as claimed in claim 10, wherein said at least one characteristic includes at least one of:

(i) file type; and

(ii) file size.

12. A method as claimed in claim 10, wherein said plurality of cache hints include at least one of:

(i) sequential access;

(ii) random access;

(iii) none; and

(iv) no hint.

13. A method as claimed in claim 10, wherein selecting step is performed in response to hint defining data that is adapted in use in dependence upon measured file access performance.

14. A method as claimed in claim 13, wherein for each combination of said one or more characteristics of said computer file, said hint defining data stores data measuring file access performance for each of said plurality of different cache file hints.

15. A method as claimed in claim 13, wherein said data measuring file access performance includes data defining a rate of data access achieved using each of said plurality of different cache hints.

16. A method as claimed in claim 13, wherein said hint defining data is only update based upon performance measurements for a file determined not already to be cached.

17. A method as claimed in claim 13, wherein said hint defining data is initialised prior to measured performance data being available with data selected in dependence upon configuration characteristics of a computer upon which said file access request is made.

18. A method as claimed in claim 17, wherein said configuration characteristics include at least one of:

(i) operating system type; and

(ii) installed memory size.

20. Apparatus as claimed in claim 19, wherein said at least one characteristic includes at least one of:

(i) file type; and

(ii) file size.

21. Apparatus as claimed in claim 19, wherein said plurality of cache hints include at least one of:

(i) sequential access;

(ii) random access;

(iii) none; and

(iv) no hint.

22. Apparatus as claimed in claim 19, wherein said cache hint selector is responsive to hint defining data that is adapted in use in dependence upon measured file access performance.

23. Apparatus as claimed in claim 22, wherein for each combination of said one or more characteristics of said computer file, said hint defining data stores data measuring file access performance for each of said plurality of different cache file hints.

24. Apparatus as claimed in claim 22, wherein said data measuring file access performance includes data defining a rate of data access achieved using each of said plurality of different cache hints.

25. Apparatus as claimed in claim 22, wherein said hint defining data is only update based upon performance measurements for a file determined not already to be cached.

26. Apparatus as claimed in claim 22, wherein said hint defining data is initialised prior to measured performance data being available with data selected in dependence upon configuration characteristics of a computer upon which said file access request is made.

27. Apparatus as claimed in claim 26, wherein said configuration characteristics include at least one of:

(i) operating system type; and

(ii) installed memory size.

19. Apparatus for accessing a computer file, said apparatus comprising:

a file characteriser operable to detect at least one characteristic of said computer file;

a cache hint selector operable in dependence upon said at least one characteristic to select from among a plurality of different possible cache hints a selected cache hint to use in association with said access to said computer file; and

file access request issuer operable to issue to an operating system a file access request for said computer file accompanied by said selected cache hint.