Enhancing data caching performance

• US 9,898,419 B2
• Filed: 05/19/2017
• Issued: 02/20/2018
• Est. Priority Date: 05/07/2012
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Hyde, II, Joseph S., Roy, Subhojit
• Primary Examiner(s): Yi, David X
• Assistant Examiner(s): PUCHE, TAHILBA O
• Application Number:
  US15/599,709
• Publication Number:
  US 20170255568A1
• Time in Patent Office: 277 Days
• CPC Class Codes: G06F 12/122 of the least frequently used [LFU] type, e.g. with individual count value
• CPC Class Codes: G06F 12/123 with age lists, e.g. queue, most recently used [MRU] list or least recently used [LRU] list

Abstract

For a cache in which a plurality of frequently accessed data segments are temporarily stored, reference count information of the plurality of data segments, in conjunction with least recently used (LRU) information, is used to determine a length of time to retain the plurality of data segments in the cache according to a predetermined weight, where notwithstanding the LRU information, those of the plurality of data segments having a higher reference counts are retained longer than those having lower reference counts.

Claims

1. A method for improving caching performance in a computing environment by a processor, comprising:

in a cache in which a plurality of data segments that are frequently accessed and are temporarily stored, and in conjunction with the cache using least recently used (LRU) information;

obtaining and examining reference count information concurrent with a deduplication operation for those of the plurality of data segments retained in the cache, wherein the reference count information is a number of chunks of virtual storage that map onto a single chunk of physical storage,

using the reference count information of the plurality of data segments to add to the cache the plurality of data segments and using the reference count information, the LRU information, statistical information, and a data storage policy to determine a length of time to retain each one of the plurality of data segments in the cache according to a predetermined weight correlated to the reference count information, assigned to each one of the plurality of data segments, wherein notwithstanding yet considering the LRU information, those of the plurality of data segments having a higher reference counts are retained longer in the cache than those having lower reference counts,

determining if the reference count information of the plurality of data segments added to the cache has been updated and a predetermined time interval has expired, wherein if the reference count information has not been updated and the predetermined time interval has not expired;

re-determining if the reference count information of the plurality of data segments added to the cache has been updated and the predetermined time interval has expired following a second predetermined time interval.

2. The method of claim 1, further including obtaining the reference count information from a data deduplication engine.

3. The method of claim 1, further including, if the reference count information has not been updated and the predetermined time interval has not expired, re-determining a length of time following an expiration of the predetermined time interval, wherein the predetermined weight decreases according to the passage of the predetermined time interval.

4. The method of claim 1, further including adding to or removing from the cache portions of the plurality of data segments in the cache based on the reference count information.

5. The method of claim 1, wherein determining the length of time to retain the plurality of data segments in cache includes implementing at least one policy corresponding to each of:

the length of time to retain the plurality of data segments in cache, at least one of the plurality of data segments, and the predetermined weight.

6. The method of claim 1, wherein determining the length of time to retain the plurality of data segments in cache includes performing a deduplication operation for those of the plurality of data segments retained in the cache concurrent with the determining.

7. The method of claim 1, further including re-determining the length of time to retain the plurality of data segments in cache based on an update to the reference count information, wherein the predetermined weight decreases according to a decrease in the reference count, and increases according to an increase in the reference count.

8. A system for improving caching performance in a computing environment, comprising:

a processor device executing instructions stored in a memory, wherein the processor device;

in a cache in which a plurality of data segments that are frequently accessed and are temporarily stored, and in conjunction with the cache using least recently used (LRU) information;

obtains and examines reference count information concurrent with a deduplication operation for those of the plurality of data segments retained in the cache, wherein the reference count information is a number of chunks of virtual storage that map onto a single chunk of physical storage,

uses the reference count information of the plurality of data segments to add to the cache the plurality of data segments and using the reference count information, the LRU information, statistical information, and a data storage policy to determine a length of time to retain each one of the plurality of data segments in the cache according to a predetermined weight correlated to the reference count information, assigned to each one of the plurality of data segments, wherein notwithstanding yet considering the LRU information, those of the plurality of data segments having a higher reference counts are retained longer in the cache than those having lower reference counts,

determines if the reference count information of the plurality of data segments added to the cache has been updated and a predetermined time interval has expired, wherein if the reference count information has not been updated and the predetermined time interval has not expired;

re-determining if the reference count information of the plurality of data segments added to the cache has been updated and the predetermined time interval has expired following a second predetermined time interval.

9. The system of claim 8, wherein the processor device obtains the reference count information from a data deduplication engine.

10. The system of claim 8, wherein the processor device, if the reference count information has not been updated and the predetermined time interval has not expired, re-determines a length of time following an expiration of the predetermined time interval, wherein the predetermined weight decreases according to the passage of the predetermined time interval.

11. The system of claim 8, wherein the processor device adds to or removes from the cache portions of the plurality of data segments in the cache based on the reference count information.

12. The system of claim 8, wherein determining the length of time to retain the plurality of data segments in cache includes implementing at least one policy corresponding to each of:

the length of time to retain the plurality of data segments in cache, at least one of the plurality of data segments, and the predetermined weight.

13. The system of claim 8, wherein determining the length of time to retain the plurality of data segments in cache includes performing a deduplication operation for those of the plurality of data segments retained in the cache concurrent with the determining.

14. The system of claim 8, wherein the processor device re-determines the length of time to retain the plurality of data segments in cache based on an update to the reference count information, wherein the predetermined weight decreases according to a decrease in the reference count, and increases according to an increase in the reference count.

15. A computer program product for improving caching performance in a computing environment by a processor, the computer program product comprising a non-transitory computer-readable storage medium having computer-readable program code portions stored therein, the computer-readable program code portions comprising:

an executable portion that, in a cache in which a plurality of data segments that are frequently accessed and are temporarily stored, and in conjunction with the cache using least recently used (LRU) information;

obtains and examines reference count information concurrent with a deduplication operation for those of the plurality of data segments retained in the cache, wherein the reference count information is a number of chunks of virtual storage that map onto a single chunk of physical storage,

uses the reference count information of the plurality of data segments to add to the cache the plurality of data segments and using the reference count information, the LRU information, statistical information, and a data storage policy to determine a length of time to retain each one of the plurality of data segments in the cache according to a predetermined weight correlated to the reference count information, assigned to each one of the plurality of data segments, wherein notwithstanding yet considering the LRU information, those of the plurality of data segments having a higher reference counts are retained longer in the cache than those having lower reference counts,

determines if the reference count information of the plurality of data segments added to the cache has been updated and a predetermined time interval has expired, wherein if the reference count information has not been updated and the predetermined time interval has not expired;

re-determining if the reference count information of the plurality of data segments added to the cache has been updated and the predetermined time interval has expired following a second predetermined time interval.

16. The computer program product of claim 15, further including an executable portion that obtains the reference count information from a data deduplication engine.

17. The computer program product of claim 15, further including an executable portion that, if the reference count information has not been updated and the predetermined time interval has not expired, re-determines a length of time following an expiration of the predetermined time interval, wherein the predetermined weight decreases according to the passage of the predetermined time interval.

18. The computer program product of claim 15, further including an executable portion that adds to or removes from the cache portions of the plurality of data segments in the cache based on the reference count information.

19. The computer program product of claim 15, wherein determining the length of time to retain the plurality of data segments in cache includes implementing at least one policy corresponding to each of:

the length of time to retain the plurality of data segments in cache, at least one of the plurality of data segments, and the predetermined weight.

20. The computer program product of claim 15, wherein determining the length of time to retain the plurality of data segments in cache includes performing a deduplication operation for those of the plurality of data segments retained in the cache concurrent with the determining.

21. The computer program product of claim 15, further including an executable portion that re-determines the length of time to retain the plurality of data segments in cache based on an update to the reference count information, wherein the predetermined weight decreases according to a decrease in the reference count, and increases according to an increase in the reference count.