Multi-port memory using single-port memory cells

• US 8,374,050 B2
• Filed: 06/04/2011
• Issued: 02/12/2013
• Est. Priority Date: 06/04/2010
• Status: Expired due to Fees

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: LSI Corporation (Broadcom, Inc.)
• Inventors: Zhou, Ting, Wu, Ephrem, Liu, Sheng, Kwon, Hyuck Jin
• Primary Examiner(s): Pham, Ly D
• Application Number:
  US13/153,392
• Publication Number:
  US 20110310691A1
• Time in Patent Office: 619 Days
• Field of Search: 365/230.03, 365/230.05, 711/131, 711/144, 711/149
• US Class Current: 365/230.05
• CPC Class Codes: G06F 12/06 Addressing a physical block of locations, e.g. base addressing, module addressing, memory dedication G06F12/08 takes precedence
• CPC Class Codes: G11C 7/1075 for multiport memories each having random access ports and serial ports, e.g. video RAM
• CPC Class Codes: G11C 8/16 Multiple access memory array, e.g. addressing one storage element via at least two independent addressing line groups
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

A memory operative to provide multi-port functionality includes multiple single-port memory cells forming a first memory array. The first memory array is organized into multiple memory banks, each of the memory banks comprising a corresponding subset of the single-port memory cells. The memory further includes a second memory array including multiple multi-port memory cells and is operative to track status information of data stored in corresponding locations in the first memory array. At least one cache memory is connected with the first memory array and is operative to store data for resolving concurrent read and write access conflicts in the first memory array. The memory includes a controller operative: to receive the status information and to determine a validity of data stored in the first memory array as a function of the status information; to control a manner in which data is stored in the memory for avoiding data overflow in the cache memory; and to resolve concurrent read and write access conflicts in the first memory array during the same memory cycle.

Claims

1. A memory operative to provide multi-port access functionality, the memory comprising:

a plurality of single-port memory cells forming a first memory array, the first memory array being organized into a plurality of memory banks, each of the memory banks comprising a corresponding subset of the plurality of single-port memory cells;

a second memory array, the second memory array comprising a plurality of multi-port memory cells and being operative to store status information of data stored in corresponding locations in the first memory array;

at least one cache memory operatively connected with the first memory array, the cache memory being operative to store data for resolving concurrent read and write access conflicts to the first memory array during a same memory cycle; and

a controller operative;

to receive the status information from the second memory array and to determine a validity of data stored in the first memory array as a function of the status information;

to control a manner in which data is stored in the memory for avoiding data overflow in the cache memory as a function of the status information; and

to resolve concurrent read and write access conflicts to the first memory array during the same memory cycle.

2. The memory of claim 1, wherein the cache memory is shared among the plurality of memory banks and has a depth associated therewith, defining a number of addressable words in the cache memory, that is at least equal to a largest depth of a given one of the respective memory banks.

3. The memory of claim 1, wherein the second memory array has a depth associated therewith that is at least equal to a number of addresses in a logical address space of the memory.

4. The memory of claim 1, wherein the controller is operative to cause data corresponding to a write request to be stored at a location in the cache memory corresponding to the write request when a read request received during a same memory cycle as the write request corresponds to a same memory bank as the write request, and an entry in the second memory array corresponding to the write request indicates that data stored in the memory bank at an address corresponding to the write request is valid.

5. The memory of claim 1, wherein the second memory array has a width of one bit and a depth at least equal to a sum of respective depths of the plurality of memory banks in the first memory array.

6. The memory of claim 5, wherein the second memory array comprises a dual-port read, single-port write (2R1 W) random access memory.

7. The memory of claim 1, wherein the second memory array comprises a plurality of storage tables, each storage table corresponding to a respective one of the plurality of memory banks in the first memory array, each storage table having a depth at least equal to a depth of a corresponding memory bank.

8. The memory of claim 7, wherein each of the plurality of storage tables comprises a single-port read, single-port write (1R1W) random access memory.

9. The memory of claim 1, wherein the status information stored in the second memory array is encoded in a manner which provides a subset of the memory banks in the first memory array that contain invalid data.

10. The memory of claim 9, wherein the second memory array comprises log₂(N+1) bits for indicating a status of data in N memory banks in the first memory array plus a case where all memory banks contain valid data.

11. The memory of claim 1, wherein the second memory array has a width of N bits, where N is an integer greater than one, and a depth at least equal to a sum of respective depths of the plurality of memory banks in the first memory array.

12. The memory of claim 11, wherein the second memory array is operative to mask a prescribed subset of the N bits of an address location to be written to thereby prevent updating the subset of the N bits with new data associated with a write request.

13. The memory of claim 1, wherein the status information stored in the second memory array is encoded in a manner which indicates which corresponding memory bank in the first memory array data in the cache memory belongs to.

14. The memory of claim 1, further comprising a pipeline circuit connected between the at least one cache memory and the first memory array.

15. The memory of claim 14, wherein the pipeline circuit is operative to remove data eviction critical paths between the cache memory and the first memory array, thereby reducing memory cycle time in the memory.

16. The memory of claim 14, wherein the pipeline circuit is operative to provide at least one additional cycle for data from the cache memory to be written into a corresponding memory bank in the first memory array, thereby reducing memory cycle time in the memory.

17. The memory of claim 14, wherein the pipeline circuit comprises at least two buffers connected in a parallel configuration between the cache memory and the first memory array, wherein data to be written into a corresponding memory bank in the first memory array is stored in the at least two buffers, the controller being operative to select one of the buffers for outputting data from the memory and to select one of the buffers for writing the data into the corresponding memory bank.

18. The memory of claim 14, wherein the pipeline circuit comprises at least first and second buffer stages connected together in series between the cache memory and the first memory array.

19. The memory of claim 1, further comprising a comparator operative to compare a first memory bank identifier corresponding to data that is to be potentially evicted from the cache memory at a given address offset a_w, associated with a write request with a second memory bank identifier corresponding to the write request, and to generate a first signal indicative of whether the first memory bank identifier is equal to the second memory bank identifier, wherein the controller is operative to determine whether data stored in the cache memory at the given address offset a_w is to be evicted from the cache memory as a function of the first signal.

20. The memory of claim 1, further comprising:

a first address mapping block operative to receive a logical read address and to generate a physical read address offset and a read memory bank identifier as a function of the logical read address; and

a second address mapping block operative to receive a logical write address and to generate a physical write address offset and a write memory bank identifier as a function of the logical write address.

21. An integrated circuit, comprising:

at least one memory operative to provide multi-port access functionality, the at least one memory comprising;

a plurality of single-port memory cells forming a first memory array, the first memory array being organized into a plurality of memory banks, each of the memory banks comprising a corresponding subset of the plurality of single-port memory cells;

a second memory array, the second memory array comprising a plurality of multi-port memory cells and being operative to store status information of data stored in corresponding locations in the first memory array;

at least one cache memory operatively connected with the first memory array, the cache memory being operative to store data for resolving concurrent read and write access conflicts to the first memory array during a same memory cycle; and

a controller operative;

to receive the status information from the second memory array and to determine a validity of data stored in the first memory array as a function of the status information;

to control a manner in which data is stored in the memory for avoiding data overflow in the cache memory as a function of the status information; and

to resolve concurrent read and write access conflicts to the first memory array during the same memory cycle.

22. A memory operative to provide n-port access functionality, where n is an integer greater than one, the memory comprising:

a plurality of m-port memory cells forming a first memory array, the first memory array being organized into a plurality of memory banks, each of the memory banks comprising a corresponding subset of the plurality of m-port memory cells, where m is an integer less than n;

a second memory array, the second memory array comprising a plurality of multi-port memory cells and being operative to track status information of data stored in corresponding locations in the first memory array;

at least one cache memory operatively connected with the first memory array, the cache memory being operative to store data for resolving concurrent read and write access conflicts to the first memory array during a same memory cycle; and

a controller operative;

to receive the status information from the second memory array and to determine a validity of data stored in the first memory array as a function of the status information;

to control a manner in which data is stored in the memory for avoiding data overflow in the cache memory as a function of the status information; and

to resolve concurrent read and write access conflicts to the first memory array during the same memory cycle.

23. An electronic system, comprising:

at least one integrated circuit, the at least one integrated circuit including at least one memory operative to provide n-port access functionality, where n is an integer greater than one, the at least one memory comprising;

a plurality of m-port memory cells forming a first memory array, the first memory array being organized into a plurality of memory banks, each of the memory banks comprising a corresponding subset of the plurality of m-port memory cells, where m is an integer less than n;

a second memory array, the second memory array comprising a plurality of multi-port memory cells and being operative to track status information of data stored in corresponding locations in the first memory array;

at least one cache memory operatively connected with the first memory array, the cache memory being operative to store data for resolving concurrent read and write access conflicts to the first memory array during a same memory cycle; and

a controller operative;

to receive the status information from the second memory array and to determine a validity of data stored in the first memory array as a function of the status information;

to control a manner in which data is stored in the memory for avoiding data overflow in the cache memory as a function of the status information; and

to resolve concurrent read and write access conflicts to the first memory array during the same memory cycle.