Method of cache management to store information in particular regions of the cache according to information-type

• US 6,434,668 B1
• Filed: 09/07/1999
• Issued: 08/13/2002
• Est. Priority Date: 09/07/1999
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Fields, James Stephen Jr., Arimilli, Ravi Kumar, Arimilli, Lakshminarayana Baba
• Primary Examiner(s): Kim, Matthew
• Assistant Examiner(s): BATAILLE, PIERRE MICHE
• Application Number:
  US09/390,187
• Time in Patent Office: 1,071 Days
• Field of Search: 711/128, 711/118, 711/141, 711/129, 711/134, 711/133, 711/145
• US Class Current: 711/128
• CPC Class Codes: G06F 12/0848 Partitioned cache, e.g. separate instruction and operand caches
• CPC Class Codes: G06F 12/0864 using pseudo-associative means, e.g. set-associative or hashing
• CPC Class Codes: G06F 12/10 Address translation
• CPC Class Codes: G06F 12/127 using additional replacement algorithms

Abstract

A set associative cache includes a number of congruence classes that each contain a plurality of sets, a directory, and a cache controller. The directory indicates, for each congruence class, which of a plurality of information types each of the plurality of sets can store. At least one set in at least one of the congruence classes is restricted to storing fewer than all of the information types and at least one set can store multiple information types. When the cache receives information to be stored of a particular information type, the cache controller stores the information into one of the plurality of sets indicated by the directory as capable of storing that particular information type. By managing the sets in which sets information is stored according to information type, an awareness of the characteristics of the various information types can easily be incorporated into the cache'"'"'s allocation and victim selection policies.

Claims

1. A cache comprising:

a plurality of congruence classes that each contain a plurality of sets;

a directory that indicates, for each of the plurality of congruence classes, which of a plurality of information types each of the plurality of sets can store, wherein at least one set of at least one congruence class can store fewer than all of said plurality of information types and at least one set can store multiple ones of said plurality of information types, wherein said directory includes a plurality of information type fields that each indicate which of the plurality of information types a respective set can store; and

a cache controller that, in response to receipt by said cache of information to be stored, said information having a particular information type among said plurality of information types, stores said information into one of the plurality of sets indicated by said directory as capable of storing said particular information type.

2. The cache of claim 1, wherein said directory indicates, for at least one set, at least one of the following information types;

data, instructions, and page table entry.

3. The cache of claim 1, wherein at least one of said plurality of information types is defined by a software-allocated memory area in system memory.

4. The cache of claim 3, wherein said at least one of said plurality of information types defined by a software-allocated memory area in system memory comprises at least one of the following information types;

operating system stack memory, operating system kernel memory, and lock table memory.

5. The cache of claim 1, said cache having an associated processor, wherein said cache controller ascertains said particular information type from instruction field information received from the processor.

6. The cache of claim 1, wherein said cache controller ascertains said particular information type from an identity of a hardware requestor of said information.

7. The cache of claim 1, wherein said cache controller ascertains said particular information type from a source of said information.

8. A data processing system, comprising:

a processor; and

a cache, coupled to said processor, that includes;

a plurality of congruence classes that each contain a plurality of sets;

a directory that indicates, for each of the plurality of congruence classes, which of a plurality of information types each of the plurality of sets can store, wherein at least one set of at least one congruence class can store fewer than all of said plurality of information types and at least one set can store multiple ones of said plurality of information types, wherein said directory includes a plurality of information type fields that each indicate which of the plurality of information types a respective set can store; and

a cache controller that, in response to receipt by said cache of information to be stored, said information having a particular information type among said plurality of information types, stores said information into one of the plurality of sets indicated by said directory as capable of storing said particular information type.

9. The data processing system of claim 8, wherein said directory indicates, for at least one set, at least one of the following information types:

data, instructions, and page table entry.

10. The data processing system of claim 8, wherein at least one of said plurality of information types is defined by a software-allocated memory area in system memory.

11. The data processing system of claim 10, wherein said at least one of said plurality of information types defined by a software-allocated memory area in system memory comprises at least one of the following information types:

operating system stack memory, operating system kernel memory, and lock table memory.

12. The data processing system of claim 8, said cache having an associated processor, wherein said cache controller ascertains said particular information type from instruction field information received from the processor.

13. The data processing system of claim 8, wherein said cache controller ascertains said particular information type from an identity of a hardware requestor of said information.

14. The data processing system of claim 8, wherein said cache controller ascertains said particular information type from a source of said information.

15. A method of managing the storage of information in a set associative cache having a plurality of congruence classes that each contain a plurality of sets, said method comprising:

for each of the plurality of congruence classes, specifying which of a plurality of information types each of the plurality of sets can store by setting a respective one of a plurality of information type fields for each of said plurality of sets, wherein at least one set can store fewer than all of said plurality of information types and at least one set can store multiple ones of said plurality of information types; and

in response to receipt by said set associative cache of information to be stored, said information having a particular information type among said plurality of information types, storing said information into a set that is able to store said particular information type.

16. The method of claim 15, wherein specifying which of a plurality of information types each of the plurality of sets can store comprises specifying at least one of the following information types:

data, instructions, and page table entry.

17. The method of claim 15, wherein at least one of said plurality of information types is defined by a software-allocated memory area in system memory.

18. The method of claim 17, wherein said at least one of said plurality of information types defined by a software-allocated memory area in system memory comprises at least one of the following information types:

operating system stack memory, operating system kernel memory, and lock table memory.

19. The method of claim 15, and further comprising ascertaining said particular information type from an instruction field.

20. The method of claim 15, and further comprising ascertaining said particular information type from an identity of a hardware requestor of the information.

21. The method of claim 15, and further comprising ascertaining said particular information type from a source of said information.