Effective transaction table with page bitmap

• US 10,552,042 B2
• Filed: 11/22/2017
• Issued: 02/04/2020
• Est. Priority Date: 09/06/2017
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Jiang, Dongyan, Zheng, Hongzhong
• Primary Examiner(s): Alsip, Michael
• Application Number:
  US15/821,704
• Publication Number:
  US 20190073133A1
• Time in Patent Office: 804 Days
• Field of Search: None
• CPC Class Codes: G06F 12/0831 using a bus scheme, e.g. with bus monitoring or watching means
• CPC Class Codes: G06F 12/0868 Data transfer between cache memory and other subsystems, e.g. storage devices or host systems
• CPC Class Codes: G06F 12/1009 using page tables, e.g. page table structures
• CPC Class Codes: G06F 2212/202 Non-volatile memory
• CPC Class Codes: G06F 2212/621 Coherency control relating to peripheral accessing, e.g. from DMA or I/O device
• CPC Class Codes: G06F 2212/65 Details of virtual memory and virtual address translation
• CPC Class Codes: G06F 3/0608 Saving storage space on storage systems
• CPC Class Codes: G06F 3/0641 De-duplication techniques
• CPC Class Codes: G06F 3/068 Hybrid storage device
• CPC Class Codes: G06F 9/467 Transactional memory G06F9/528 takes precedence

Abstract

A transaction manager for use with memory is described. The transaction manager can include a write data buffer to store outstanding write requests, a read data multiplexer to select between data read from the memory and the write data buffer, a command queue and a priority queue to store requests for the memory, and a transaction table to track outstanding write requests, each write request associated with a state that is Invalid, Modified, or Forwarded.

Claims

1. A transaction manager for use in a memory subsystem with memory, comprising:

a write data buffer to store data for outstanding write requests to be written to memory;

a read data multiplexer to select between data read from the write data buffer and the memory;

a command queue to store write requests and internal read requests for the memory;

a priority queue to store external read requests for the memory; and

a transaction table to track the outstanding write requests, each outstanding write request associated with a state drawn from a set including Invalid, Modified, and Forwarded.

2. A transaction manager according to claim 1, further comprising a write coalescing buffer to merge partial write requests with other data, the other data drawn from a set including data in the memory and data in the write data buffer.

3. A transaction manager according to claim 1, wherein the transaction manager supports early acknowledgement of write requests from a host computer before completing the write requests by the memory.

4. A transaction manager according to claim 1, wherein the memory includes a dedupable memory.

5. A transaction manager according to claim 1, wherein the transaction table includes at least one entry, each entry including a page state, a transaction identifier (ID), a page logical address, and an entry bitmap.

6. A method, comprising:

receiving a request at a transaction manager for memory from a host computer;

determining that the request may be satisfied based at least in part on a write data buffer in the transaction manager; and

satisfying the request using at least one of the write data buffer and the memory including;

determining that a transaction table in the transaction manger includes an entry associated with a Modified flag that includes an address for data to be written to the memory; and

based at least in part on the write data buffer including the entry, merging the data to be written with a page in the write data buffer corresponding to the entry.

7. A method according to claim 6, wherein the request includes a read request requesting data.

8. A method according to claim 7, wherein:

determining that the request may be satisfied based at least in part on a write data buffer in the transaction memory includes determining that the data requested in the read request may be found in the write data buffer; and

satisfying the request using at least one of the write data buffer and the memory includes, based at least in part on the data requested in the read request being found in the write data buffer;

reading the data requested in the read request from the write data buffer; and

sending the data requested in the read request to the host computer.

9. A method according to claim 8, wherein satisfying the request using at least one of the write data buffer and the memory further includes, based at least in part on the data requested in the read request not being found in the write data buffer:

placing the read request in a priority queue in the transaction manager for the memory;

receiving the data requested in the read request from the memory; and

sending the data requested in the read request to the host computer.

10. A method according to claim 6, wherein:

the request includes a write request requesting the data be written to the memory; and

satisfying the request using at least one of the write data buffer and the memory includes sending an early acknowledgement to the host computer before completing the write requests by the memory.

11. A method according to claim 10, wherein satisfying the request using at least one of the write data buffer and the memory further includes, based at least in part on the transaction table not including the entry associated with the Modified flag that includes the address for the data to be written to the memory:

determining that the data to be written to the memory includes a full data write; and

based at least in part on the data to be written to the memory including a full data write;

writing the data to be written to the write data buffer;

adding a new entry to the transaction table associated with the Modified flag; and

placing the write request in a command queue in the transaction manager for the memory.

12. A method according to claim 11, wherein satisfying the request using at least one of the write data buffer and the memory further includes, based at least in part on the transaction table not including the entry associated with the Modified flag that includes the address for the data to be written to the memory and the data to be written to the memory does not include a full data write:

reading a full cache line from at least one of the write data buffer and the memory;

merging the data to be written with the full cache line;

adding the new entry to the transaction table associated with the Modified flag for the merged full cache line; and

placing the write request in a command queue in the transaction manager for the memory.

13. A method according to claim 12, wherein reading a full cache line from at least one of the write data buffer and the memory includes:

based at least in part on the transaction table including the entry associated with a Forwarded flag that includes the address for the data to be written to the memory, reading the full cache line from the write data buffer; and

based at least in part on the transaction table not including the entry associated with the Forwarded flag that includes the address for the data to be written to the memory;

placing a read request for the full cache line in a command queue in the transaction manager for the memory; and

receiving the full cache line from the memory.

14. A method according to claim 6, further comprising:

receiving a notification from the memory that a write request was removed from the command queue; and

changing a Modified flag associated with an entry in a transaction table for the write request to a Forwarded flag.

15. A method according to claim 14, further comprising:

receiving an acknowledgement from the memory; and

changing the Forwarded flag associated with the entry in the transaction table for the write request to an Invalid flag.

16. An article, comprising a non-transitory storage medium, the non-transitory storage medium having stored thereon instructions that, when executed by a machine, result in:

receiving a request at a transaction manager for memory from a host computer;

determining that the request may be satisfied using a write data buffer in the transaction manager; and

satisfying the request using at least one of the write data buffer and the memory including;

determining that a transaction table in the transaction manger includes an entry associated with a Modified flag that includes an address for data to be written to the memory; and

based at least in part on the write data buffer including the entry associated with the Modified flag that includes the address for the data to be written to the memory, merging the data to be written with a page in the write data buffer corresponding to the entry in the transaction manager associated with the Modified flag.

17. An article according to claim 16, wherein:

the request includes a write request requesting the data be written to the memory; and

satisfying the request using at least one of the write data buffer and the memory includes sending an early acknowledgement to the host computer before completing the write requests by the memory.

18. An article according to claim 17, wherein satisfying the request using at least one of the write data buffer and the memory further includes, based at least in part on the transaction table not including the entry associated with the Modified flag that includes the address for the data to be written to the memory:

determining that the data to be written to the memory includes a full data write; and

based at least in part on the data to be written to the memory including a full data write;

writing the data to be written to the write data buffer;

adding a new entry to the transaction table associated with the Modified flag; and

placing the write request in a command queue in the transaction manager for the memory.