Set partitioning for cache memories
A method, apparatus, and signal-bearing medium for improving the performance of a cache when request streams with different spatial and/or temporal properties access the cache. A set in the cache is partitioned into subsets with different request streams using different subsets within the cache. In this way, interference between the different request streams is reduced.
1. A method comprising:
dividing requests to a cache into a plurality of logical streams;
assigning each of the requests a stream identifier; and
dividing a set in the cache into a plurality of subsets corresponding to the plurality of logical streams;
wherein dividing the set further comprises:
dividing the set into first and second subsets, each corresponding to a respective stream in the plurality of logical streams, wherein the first subset comprises X ways and the second subset comprises S−X ways, wherein X comprises a positive integer greater than zero, and S comprises a number of ways in the set and S is a positive integer greater than X, and wherein X is a configurable parameter.
2. The method of claim 1 , further comprising:
determining whether an address associated with a request has data in the set.
3. The method of claim 2 , further comprising:
when the address does not have data in the set, allocating a block into one of the plurality of subsets corresponding to the stream associated with the block.
4. The method of claim 2 , further comprising:
when the address does have data in the set, returning the data to a requester.
5. A method comprising:
dividing requests to a cache into a plurality of logical streams;
assigning each of the requests a stream identifier; and
dividing a set in the cache into a plurality of subsets corresponding to the plurality of logical streams;
wherein dividing the set further comprises:
dividing the set into a plurality of subsets, each corresponding to a respective stream in the plurality of logical streams, wherein each subset comprises S/M ways, wherein S comprises a number of ways in the set and M comprises a number of the plurality of logical streams, and wherein S is an integer multiple of M and M is a positive integer greater than zero, and wherein M is a configurable parameter.
6. The method of claim 5 , further comprising:
determining whether an address associated with a request has data in the set.
7. The method of claim 6 , further comprising:
when the address does not have data in the set, allocating a block into one of the plurality of subsets corresponding to the stream associated with the block.
8. The method of claim 6 , further comprising:
when the address does have data in the set, returning the data to a requester.
9. A signal-bearing medium comprising instructions, which when read and executed by a processor comprise:
partitioning a set in a cache into a plurality of subsets corresponding to a plurality of streams; and
allocating a block in a first subset of the plurality of subsets, wherein the first subset is associated with a first stream of the plurality of streams, which is associated with a request, which is associated with the block;
wherein the partitioning further comprises:
dividing the set into the first subset and a second subset, wherein the first subset comprises X ways and the second subset comprises S−X ways, wherein X comprises a positive integer greater than zero, and S comprises a number of ways in the set and S is a positive integer greater than X, and wherein X is a configurable parameter.
10. The signal-bearing medium of claim 9 , wherein the allocating further comprises:
assigning the request a stream identifier.
11. The method of claim 9 , wherein X is found in a configuration file.
12. The method of claim 9 , wherein X is changed by an application.
13. the method of claim 9 , wherein X is changed by a user of an application.
14. The method of claim 9 , wherein X is changed by a compiler.
15. A signal-bearing medium comprising instructions, which when read and executed by a processor comprise:
partitioning a set in a cache into a plurality of subsets corresponding to a plurality of streams; and
allocating a block in a first subset of the plurality of subsets, wherein the first subset is associated with a first stream of the plurality of streams, which is associated with a request, which is associated with the block;
wherein the partitioning further comprises:
dividing the set into the plurality of subsets, wherein the each subset comprises S/M ways, wherein S comprises a number of ways in the set and M comprises a number of the plurality of streams, and wherein S is an integer multiple of M and M is a positive integer greater than zero, and wherein M is a configurable parameter.
16. The signal-bearing medium of claim 15 , wherein the allocating further comprises:
assigning the request a stream identifier.