Memory record update filtering

• US 20030140203A1
• Filed: 03/11/2003
• Published: 07/24/2003
• Est. Priority Date: 12/30/1999
• Status: Active Grant

• Current Assignee: Michael Bekerman, Ronny Ronen, Stephan J. Jourdan
• Original Assignee: Michael Bekerman, Ronny Ronen, Stephan J. Jourdan
• Inventors: Jourdan, Stephan J., Ronen, Ronny, Bekerman, Michael
• Granted Patent: US 6,678,808 B2
• Time in Patent Office: Days
• US Class Current: 711/159
• CPC Class Codes: G06F 12/126 with special data handling, e.g. priority of data or instructions, handling errors or pinning
• CPC Class Codes: G06F 9/3806 using address prediction, e.g. return stack, branch history buffer

Abstract

Apparatus and methods to filter memory record updates. A microprocessor can include a memory record update filter. The memory record update filter can include a table memory populated by a plurality of data entries. Each data entry can include a data tag field to store a data tag, a data field to store a data value, and a filter field to store a filter value. A first comparator can be in communication with the data tag field of the table memory and a data accessing information input to perform a data tag comparison. A second comparator can be in communication with the filter field of the table memory and a data value input. A control circuit can be in communication with the table memory, the first comparator, and the second comparator.

Claims

1. A method of filtering data record updates in a memory having a data side and a filter side on a microprocessor, the method comprising:

receiving a data value in the memory;

comparing filter table accessing information to data contents of the filter side, said filter table accessing information based on the data value and associated data table accessing information; and

if the filter table accessing information comparison indicates a match;

updating the data side based on the data value, and

updating the filter side based on the filter table accessing information.

2. The method of claim 1, wherein said updating the filter side based on the filter table accessing information comprises:

updating at least one of said filter tag field and a counter associated with said filter tag field based on the filter table accessing information.

3. The method of claim 1, further comprising:

if the filter table accessing information comparison indicates no match;

updating the filter side based on the filter table accessing information; and

comparing the associated data table accessing information to data contents of the data side; and

if the associated data table accessing information comparison indicates a match;

updating the data side based on the data value.

4. The method of claim 1, wherein comparing filter table accessing information to data contents of the filter side comprises:

determining the filter table accessing information from the data value and the associated data table accessing information; and

comparing the filter table accessing information to a data field on the filter side.

5. The method of claim 1, wherein updating the data side based on the data value comprises:

if a counter on the filter side that is associated with the matched data contents of the filter side is at least equal to a predetermined value, updating the filter side based on the filter table accessing information.

6. The method of claim 5, further comprising:

if the filter table accessing information comparison indicates no match;

updating the filter side based on the filter table accessing information; and

if comparing the associated data table accessing information to data contents on the data side indicates a match, updating the data side based on the data value.

7. The method of claim 6, wherein updating the data side based on the data value comprises:

updating said data field based on the data value.

8. The method of claim 6, wherein updating the data side based on the data value comprises:

updating a data tag field based on the data value.

9. The method of claim 6, wherein updating the filter side based on the filter table accessing information comprises:

updating said filter tag field based on the filter table accessing information.

10. A filtered memory comprising:

a pair of memories;

a first comparator to perform a data tag comparison, said first comparator in communication with a data tag field of a first memory of said pair of memories and a data record accessing information input;

a second comparator in communication with a filter tag field of a second memory of said pair of memories and a data value input; and

a control circuit in communication with said first comparator and said second comparator.

11. The filtered memory of claim 10, further comprising:

a selection circuit coupled to the data value input and the data accessing information input, said selection circuit including an output in communication with said second memory and said second comparator.

12. The filtered memory of claim 10, wherein each filter tag field has an associated relevance counter field to store a relevance counter value.

13. The filtered memory of claim 12, further comprising a third comparator in communication with said relevance counter field and a relevance threshold value input.

14. The filtered memory of claim 13, wherein an output of said third comparator is in communication with said control circuit.

15. The filtered memory of claim 10, wherein said control circuit comprises:

an AND gate coupled to said second comparator and said third comparator; and

an OR gate coupled to said AND gate and said first comparator; and

said control circuit to control the output of a data record update enable signal.

16. The filtered memory of claim 10, wherein said pari of memories is populated with a plurality of data entries.

17. The filtered memory of claim 16, wherein each data entry is to store a predicted value.

18. The filtered memory of claim 16, wherein each data entry is to store a branch target address;

and

the data accessing information input is to receive at least a portion of a branch instruction address.

19. The filtered memory of claim 16, wherein each data entry is to store a memory operation address;

and

the data accessing information input is to receive at least a portion of an instruction address.

20. The filtered memory of claim 16, wherein each said data entry further including said relevance counter field.

21. A machine-readable medium having stored therein a program, the program having machine-executable instructions to filter data record updates in a memory having a data side and a filter side on a microprocessor, the machine-executable instructions comprising instructions to:

receive a data value in the memory;

compare filter table accessing information to data contents of the filter side, said filter table accessing information based on the data value and associated data table accessing information; and

if the filter table accessing information comparison indicates a match;

update the data side based on the data value, and

update the filter side based on the filter table accessing information.

22. The machine-readable medium of claim 21, wherein said update the filter side based on the filter table accessing information instruction comprises:

update at least one of said filter tag field and a counter associated with said filter tag field based on the filter table accessing information.

23. The machine-readable medium of claim 21, further comprising instructions to:

if the filter table accessing information comparison indicates no match;

update the filter side based on the filter table accessing information; and

compare the associated data table accessing information to data contents of the data side; and

if the associated data table accessing information comparison indicates a match;

update the data side based on the data value.

24. The machine-readable medium of claim 21, wherein the comparing filter table accessing information to data contents of the filter side instruction comprises instructions to:

determine the filter table accessing information from the data value and the associated data table accessing information; and

compare the filter table accessing information to a data field on the filter side.

25. The machine-readable medium of claim 21, wherein the update the data side based on the data value instruction comprises:

if a counter on the filter side that is associated with the matched data contents of the filter side is at least equal to a predetermined value, update the filter side based on the filter table accessing information.

26. A filtered memory comprising:

a plurality of first entries, each of said plurality of first entries having at least a tag field;

a comparator coupled to said tag fields of the plurality of first entries and having an input for address data;

a plurality of second entries, each of said plurality of second entries having a field to store data; and

each of said plurality of second entries field to store data being configured to store data upon a hit in the plurality of first entries.

27. The filtered memory of claim 26, further comprising:

a selection circuit coupled to said tag fields of said plurality of first entries and a data accessing information input, said selection circuit including an output in communication with said plurality of second entries and a second comparator.

28. The filtered memory of claim 26, wherein each of said plurality of first entries tag fields has an associated relevance counter field to store a relevance counter value.

29. A memory management method comprising, during an attempt to store a data item in the memory:

determining whether there has been a prior attempt to store the data item in the memory, and

storing the data item in the memory only if there have been a threshold number of prior attempts to store the data item in the memory.

30. The method of claim 29, wherein the threshold number is one.

31. The method of claim 30, wherein it is determined that there has been a prior attempt when a data item index hits a first memory section;

and

in response to the hit, the data item is stored in a second memory section.

32. The method of claim 29, wherein the determining comprises:

reading from a first memory section a count value of prior attempts to store the data item; and

the storing includes storing the data item in a second memory section.

33. The method of claim 32, further comprising:

if there is no count value stored in the first memory section, allocating an entry in the first memory section for the data item.

34. The method of claim 32, wherein the first and second memories each have tag fields.