Software-controlled cache set management with software-generated class identifiers

• US 7,114,035 B2
• Filed: 09/04/2003
• Issued: 09/26/2006
• Est. Priority Date: 09/04/2003
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation, Sony Interactive Entertainment Inc. (Sony Group Corp.)
• Original Assignee: International Business Machines Corporation
• Inventors: Johns, Charles Ray, Hofstee, Harm Peter, Truong, Thuong Quang, Yamazaki, Takeshi, Shippy, David, Day, Michael Norman, Kahle, James Allan
• Primary Examiner(s): Padmanabhan, Mano
• Assistant Examiner(s): Doan, Duc T
• Application Number:
  US10/655,365
• Publication Number:
  US 20050055505A1
• Time in Patent Office: 1,118 Days
• Field of Search: None
• US Class Current: 711/133
• CPC Class Codes: G06F 12/126 with special data handling, e.g. priority of data or instructions, handling errors or pinning

Abstract

The present invention provides for selectively overwriting sets of a cache as a function of a replacement management table and a least recently used function. A class identifier is created as a function of an address miss. A replacement management table is employable to read the class identifier to create a tag replacement control indicia. The cache, comprising a plurality of sets, is employable to disable the replacement of at least one of the plurality of sets as a function of the tag replacement control indicia.

Claims

1. A computing system, comprising:

a plurality of memory regions each having a different address range and a corresponding class identifier;

a range register coupled to receive an address and configured to produce;

(i) the class identifier corresponding to the memory region having an address range that includes the received address, or (ii) a default class identifier in the event that none of the memory regions has an address range that includes the received address;

a cache comprising a plurality of sets;

a replacement management table (RMT) having a plurality of entries, wherein each of the entries corresponds to one of the class identifiers and to one of the sets of the cache, and wherein the entries of the RMT are configured to store data that define the sets of the cache that may be used to store data retrieved from each of the memory regions, and wherein the RMT is coupled to receive the class identifier produced by the range register and configured to produce a tag replacement control indicia dependent on the received class identifier, and wherein the tag replacement control indicia is indicative of the sets of the cache that may be used to store data retrieved from one of the memory regions having the received class identifier; and

wherein the cache is coupled to receive data retrieved from one of the memory regions and the tag replacement control indicia, and configured to store the received data in one of the sets of the cache dependent upon the tag replacement control indicia.

2. The computing system of claim 1, wherein the class identifiers are created by software, and wherein the class identifier creation software comprises compiler or operating system software.

3. The computing system of claim 1, wherein a set of the cache is replaced based upon a least recently used function.

4. The computing system of claim 1, wherein the replacement management table uses software.

5. The computing system of claim 4, wherein class identifier creation software is employable to classify an address range as a default address range.

6. The computing system of claim 1, wherein the cache comprises a translation lookaside buffer.

7. The computing system of claim 4, wherein class identifier generation software further comprises a direct memory access command.

18. The computing system of claim 1, wherein the RMT is configured to store a plurality of bypass bits each corresponding to a different one of the class identifiers, and wherein each of the bypass bits is indicative of whether data retrieved from one of the memory regions having the corresponding class identifier is to be stored in the cache, and wherein the tag replacement control indicia produced by the RMT is indicative of the bypass bit corresponding to the class identifier produced by the range register.

19. The computing system of claim 1, wherein the RMT is configured to store a plurality of algorithm bits each corresponding to a different one of the class identifiers, and wherein each of the algorithm bits specifies a replacement algorithm to be used to replace data in the cache for the corresponding class identifier, and wherein the tag replacement control indicia produced by the RMT is indicative of the algorithm bit corresponding to the class identifier produced by the range register.

8. A method of configuring replacement eligibility of at least one set in a cache comprising a plurality of sets, the method comprising:

creating a class identifier for each of a plurality of memory regions having a different address range by class identifier creation software;

receiving an address;

using the address to produce;

(i) the class identifier corresponding to the memory region having an address range that includes the received address, or (ii) a default class identifier in the event that none of the memory regions has an address range that includes the received address;

using the produced class identifier to create a tag replacement control indicia through employment of a replacement management table, wherein the tag replacement control indicia is indicative of the sets of the cache that may be used to store data retrieved from one of the memory regions having the produced class identifier; and

configuring the replacement eligibility of the at least one set in the cache as a function of the tag replacement control indicia.

9. The method of claim 8, wherein the step of using the produced class identifier to create a tag replacement control indicia further comprises employing a software-managed replacement management table.

10. The method of claim 8, further comprising replacing data within the at least one set of the cache as a function of the tag replacement control indicia.

11. The method of claim 8, further comprising discarding the tag replacement control indicia in the event data corresponding to the received address resides in the cache.

12. The method of claim 8, further comprising the step of using the received address to retrieve corresponding data.

13. The method of claim 10, wherein the replacing is carried out using a least recently used function.

14. The method of claim 10, wherein the replacing comprises:

using an algorithm bit to select a replacement algorithm; and

using the replacement algorithm to replace data within the at least one set of the cache dependent upon the tag replacement control indicia.

15. A computer program product for configuring replacement eligibility of at least one set in a cache comprising a plurality of sets, the computer program product having a medium with a computer program embodied thereon, the computer program comprising:

computer code for creating a class identifier for each of a plurality of memory regions, wherein each of the memory regions has a different address range;

computer code for using a received address to produce;

(i) the class identifier corresponding to the memory region having an address range that includes the received address, or (ii) a default class identifier in the event that none of the memory regions has an address range that includes the received address;

computer code for using the produced class identifier to create a tag replacement control indicia through employment of a replacement management table, wherein the tag replacement control indicia is indicative of the sets of the cache that may be used to store data retrieved from one of the memory regions having the produced class identifier; and

computer code for configuring the replacement eligibility of the at least one set in the cache as a function of the tag replacement control indicia.

16. The computer program product of claim 15, further comprising computer code for replacing data within one of the sets of the cache as a function of the tag replacement control indicia.

17. A processor comprising:

a plurality of memory regions each having a different address range;

a cache comprising a plurality of sets;

computer code for creating a class identifier for each of the memory regions;

computer code for using a received address to produce;

(i) the class identifier corresponding to the memory region having an address range that includes the received address, or (ii) a default class identifier in the event that none of the memory regions has an address range that includes the received address;

computer code for using the produced class identifier to create a tag replacement control indicia through employment of a replacement management table, wherein the tag replacement control indicia is indicative of the sets of the cache that may be used to store data retrieved from one of the memory regions having the produced class identifier; and

computer code for configuring the replacement eligibility of the at least one set in the cache as a function of the tag replacement control indicia.