Method and devices for managing cache

Patent metadata

Field	Value
Publication number	US-11366758-B2
Application number	US-202016989496-A
Country	US
Kind code	B2
Filing date	Aug 10, 2020
Priority date	Jun 2, 2017
Publication date	Jun 21, 2022
Grant date	Jun 21, 2022

Abstract

Embodiments of the present disclosure relate to a method and apparatus for managing cache. The method comprises determining a cache flush time period of the cache for a lower-layer storage device associated with the cache. The method further comprises: in response to a length of the cache flush time period being longer than a threshold length of time, in response to receiving a write request, determining whether data associated with the write request has been stored into the cache. The method further comprises: in response to a miss of the data in the cache, storing the write request and the data in the cache without returning a write completion message for the write request.

First claim

We claim:

1. A method of managing cache, comprising:
determining a cache flush time period of the cache for a lower-layer storage device associated with the cache;
in response to determining the cache flush time period, comparing the determined cache flush time period to a preset threshold amount of time;
in response to the determining that the determined cache period exceeds the preset threshold amount of time:
in response to receiving a write request, determining whether data associated with the write request has been stored into the cache;
in response to a miss of the data in the cache, storing the write request and the data in the cache without returning a write completion message for the write request;
comparing a first length of time of the write request being stored in the cache and a predefined second length of time;
in response to the first length of time exceeding the second length of time, determining a dirty block rate in the cache associated with the storage device; and
in response to the dirty block rate being lower than a predetermined threshold, sending the write completion message for the write request.

2. The method according to claim 1 , further comprising:
determining a first number of storage blocks in the cache that are released by a flush to the storage device and are available for the storage device; and
in response to the number being greater than a second number of storage blocks occupied by the data, sending the write completion message for the write request.

3. The method according to claim 1 , wherein determining the cache flush time period for the storage device comprises:
obtaining a plurality of historical flush time periods for a plurality of previous flushes from the cache to the storage device; and
determining the cache flush time period by averaging the plurality of historical flush time periods.

4. The method according to claim 2 , further comprising:
in response to sending the write completion message, subtracting the second number from the first number.

5. The method according to claim 1 , further comprising:
determining a first number of storage blocks in the cache that are released by a flush to the storage device and are available for the storage device;
obtaining the number of storage blocks in the cache and the number of dirty blocks in the cache; and
determining the dirty block rate based on the first number, the number of storage blocks in the cache, and the number of dirty blocks in the cache.

6. A cache manager, the cache comprising a plurality of storage blocks, the cache manager comprising:
a processor; and
a memory having computer program instructions stored thereon, the processor executing the computer program instructions in the memory to control the memory system to perform acts comprising:
determining a cache flush time period of the cache for a lower-layer storage device associated with the cache;
in response to determining the cache flush time period, comparing the determined cache flush time period to a preset threshold amount of time;
in response to the determining that the determined cache period exceeds the preset threshold amount of time:
in response to receiving a write request, determining whether data associated with the write request has been stored into the cache;
in response to a miss of the data in the cache, storing the write request and the data in the cache without returning a write completion message for the write request;
comparing a first length of time of the write request being stored in the cache and a predefined second length of time;
in response to the first length of time exceeding the second length of time, determining a dirty block rate in the cache associated with the storage device; and
in response to the dirty block rate being lower than a predetermined threshold, sending the write completion message for the write request.

7. The manager according to claim 6 , further comprising:
determining a first number of storage blocks in the cache that are released by a flush to the storage device and are available for the storage device;
in response to the number being greater than a second number of storage blocks occupied by the data, sending the write completion message for the write request.

8. The manager according to claim 6 , wherein determining the cache flush time period for the storage device comprises:
obtaining a plurality of historical flush time periods for a plurality of previous flushes from the cache to the storage device; and
determining the cache flush time period by averaging the plurality of historical flush time periods.

9. The manager according to claim 7 , further comprising:
in response to sending the write completion message, subtracting the second number from the first number.

10. The manager according to claim 6 , further comprising:
determining a first number of storage blocks in the cache that are released by a flush to the storage device and are available for the storage device;
obtaining the number of storage blocks in the cache and the number of dirty blocks in the cache; and
determining the dirty block rate based on the first number, the number of storage blocks in the cache, and the number of dirty blocks in the cache.

11. A computer program product for managing cache, comprising:
a non-transitory computer readable medium encoded with computer-executable code, the code configured for the execution of:
determining a cache flush time period of the cache for a lower-layer storage device associated with the cache;
in response to determining the cache flush time period, comparing the determined cache flush time period to a preset threshold amount of time; and
in response to the determining that the determined cache period exceeds the preset threshold amount of time:
in response to receiving a write request, determining whether data associated with the write request has been stored into the cache,
in response to a miss of the data in the cache, storing the write request and the data in the cache without returning a write completion message for the write request,
comparing a first length of time of the write request being stored in the cache and a predefined second length of time,
in response to the first length of time exceeding the second length of time, determining a dirty block rate in the cache associated with the storage device, and
in response to the dirty block rate being lower than a predetermined threshold, sending the write completion message for the write request.

12. The computer program product of claim 11 , the code further configured for the execution of:
determining a first number of storage blocks in the cache that are released by a flush to the storage device and are available for the storage device; and
in response to the number being greater than a second number of storage blocks occupied by the data, sending the write completion message for the write request.

13. The computer program product of claim 11 , wherein determining the cache flush time period for the storage device comprises:
obtaining a plurality of historical flush time periods for a plurality of previous flushes from the cache to the storage device; and
determining the cache flush time period by averaging the plurality of historical flush time periods.

14. The computer program product of claim 12 , the code further configured for the execution of:
in response to sending the write completion message, subtracting the second number from the first number.

15. The computer program product of claim 11 , the code further configured for the execution of:
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Assignees

• Emc Ip Holding Co Llc

Inventors

• Jia Ruiyong
• Xu Xinlei
• Yang Lifeng
• Li Xiongcheng
• Gao Jian

Classifications

• G06F12/0868 Primary

  Data transfer between cache memory and other subsystems, e.g. storage devices or host systems · CPC title

• G06F3/061 Primary

  Improving I/O performance · CPC title

• G06F2201/81

  Threshold · CPC title

• G06F12/0891

  using clearing, invalidating or resetting means · CPC title

• G06F3/0638

  Organizing or formatting or addressing of data · CPC title