Temporal tracking of cache data
View Patent ↗A data storage system with a cache organizes cache windows into lists based on the number of cache lines accessed during input/output operations. The lists are maintained in temporal queues with cache windows transferred from prior temporal queues to a current temporal queue. Cache windows are removed from the oldest temporal queue and least accessed cache window list whenever cached data needs to be removed for new hot data.
1. A computer apparatus, comprising:
a processor;
memory connected to the processor, at least a portion of the memory comprising a cache; and
computer executable program code configured to execute on the processor,
wherein the computer executable program code is configured to:
receive an input/output operation;
identify a cache window associated with data to be accessed pursuant to the input/output operation;
remove the cache window from a prior temporal queue; and
add the cache window to a current temporal queue comprising a plurality of cache window lists, each of the plurality of cache window lists configured to store one or more pointers to one or more cache windows.
2. The computer apparatus of claim 1 , wherein each of the one or more cache window lists comprises a hash table.
3. The computer apparatus of claim 1 , wherein:
the computer executable program code is further configured to determine a cache window list in the current temporal queue based on a feature of the input output/output operation; and
adding the identified cache window to the current temporal queue comprises adding the identified cache window to the determined cache window list.
4. The computer apparatus of claim 3 , wherein the feature of the input/output operation comprises a number of cache lines accessed during the input/output operation.
5. The computer apparatus of claim 1 , wherein:
each of the prior temporal queue and current temporal queue are defined by a threshold number of input/output operations; and
the computer executable program code is further configured to increment a counter of input/output operations.
6. The computer apparatus of claim 5 , wherein the computer executable program code is further configured to alter the threshold number of input/output operations.
7. A data storage system, comprising:
a processor;
one or more data storage elements connected to the processor;
memory connected to the processor, at least a portion of the memory comprising a cache for the one or more data storage elements; and
computer executable program code configured to execute on the processor,
wherein the computer executable program code is configured to:
receive an input/output operation directed toward data in the cache;
identify a cache window associated with data to be accessed pursuant to the input/output operation;
remove the cache window from a prior temporal queue; and
add the cache window to a current temporal queue comprising a plurality of cache window lists, each of the plurality of cache window lists configured to store one or more pointers to one or more cache windows.
8. The data storage system of claim 7 , wherein each of the one or more cache window lists comprises a hash table.
9. The data storage system of claim 7 , wherein:
the computer executable program code is further configured to determine a cache window list in the current temporal queue based on a feature of the input/output operation; and
adding the identified cache window to the current temporal queue comprises adding the identified cache window to the determined cache window list.
10. The data storage system of claim 9 , wherein the feature of the input/output operation comprises a number of cache lines accessed during the input/output operation.
11. The data storage system of claim 7 , wherein:
each of the prior temporal queue and current temporal queue are defined by a threshold number of input/output operations; and
the computer executable program code is further configured to increment a counter of input/output operations.
12. The data storage system of claim 11 , wherein the computer executable program code is further configured to alter the threshold number of input/output operations.
13. A method for maintaining hot data in a data storage system cache, comprising:
receiving an input/output operation directed toward data in a cache;
identifying a cache window associated with the data in the cache;
removing the cache window from a prior temporal queue; and
adding the cache window to a current temporal queue comprising a plurality of cache window lists, each of the plurality of cache window lists configured to store one or more pointers to one or more cache windows.
14. The method of claim 13 , further comprising:
determining a cache window list in the current temporal queue based on a feature of the input/output operation,
wherein adding the identified cache window to the current temporal queue comprises adding the identified cache window to the determined cache window list.
15. The method of claim 14 , wherein the feature of the input/output operation comprises a number of cache lines accessed during the input/output operation.
16. The method of claim 13 , further comprising:
incrementing a counter of input/output operations,
wherein each of the prior temporal queue and current temporal queue are defined by a threshold number of input/output operations.
17. The method of claim 16 , further comprising altering the threshold number of input/output operations.