METHOD AND APPARATUS FOR IMPLEMENTING TRANSACTION MEMORY

• US 20090119667A1
• Filed: 11/06/2008
• Published: 05/07/2009
• Est. Priority Date: 11/07/2007
• Status: Abandoned Application

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Shen, Xiaowei, Hou, Rui, Wang, Hua Yong
• Application Number:
  US12/265,788
• Publication Number:
  US 20090119667A1
• Time in Patent Office: Days
• US Class Current: 718/101
• CPC Class Codes: G06F 9/467 Transactional memory G06F9/528 takes precedence

Abstract

A method and apparatus for implementing transactional memory (TM). The method includes: allocating a hardware-based transaction footprint recorder to the transaction, for recording footprints of the transaction when a transaction is begun; determining that the transaction is to be switched out; and switching out the transaction, where the footprints of the switched-out transaction are still kept in the hardware-based transaction footprint recorder. According to the present invention, transaction switching is supported by TM, and the cost of conflict detection between an active transaction and a switched-out transaction is greatly reduced since the footprints of the switched-out transaction are still kept in the hardware-based transaction footprint recorder.

Claims

1. A method for implementing transaction memory, comprising the steps of:

allocating a hardware-based transaction footprint recorder to a transaction, for recording footprints of said transaction when the transaction is begun;

determining that said transaction is to be switched out; and

switching out said transaction;

wherein the footprints of said switched-out transaction are kept in said hardware-based transaction footprint recorder.

2. The method according to claim 1, wherein said hardware-based transaction footprint recorder is shared by multiple processor cores.

3. The method according to claim 1, wherein said hardware-based transaction footprint recorder is allocated to multiple transactions simultaneously by incorporating a color bit for identifying to which transaction the footprints belong in each entry of footprints of a transaction.

4. The method according to claim 1, wherein said method further comprises the step of:

accessing a color register to determine whether said hardware-based transaction footprint recorder can be allocated to said transaction.

5. The method according to claim 1, further comprising the step of:

switching in said switched-out transaction.

6. The method according to claim 1, further comprising the step of:

aborting said switched-out transaction.

7. The method according to claim 1, wherein all other transactions belonging to the same thread as that to which said transaction belongs are allocated to said hardware-based transaction footprint recorder.

8. The method according to claim 1, wherein said hardware-based transaction footprint recorder is a dedicated buffer or a cache associated with one of multiple processor cores.

9. The method according to claim 1, wherein the footprints of said transaction comprise:

memory addresses from which said transaction reads data;

memory addresses to which said transaction writes data; and

data to be written.

10. An apparatus for implementing transaction memory, wherein said apparatus comprises:

means for allocating a hardware-based transaction footprint recorder to a transaction for recording footprints of said transaction when the transaction is begun;

means for determining that said transaction is to be switched out; and

means for switching out said transaction;

wherein the footprints of said switched-out transaction are kept in said hardware-based transaction footprint recorder.

11. The apparatus according to claim 10, wherein said hardware-based transaction footprint recorder is shared by multiple processor cores.

12. The apparatus according to claim 10, wherein said hardware-based transaction footprint recorder is allocated to multiple transactions simultaneously by incorporating a color bit for identifying to which transaction the footprints belong in each entry of footprints of a transaction.

13. The apparatus according to claim 10, wherein said apparatus further comprises:

means for accessing a color register to determine whether said hardware-based transaction footprint recorder can be allocated to said transaction.

14. The apparatus according to claim 10, further comprising:

means for switching in said switched-out transaction.

15. The apparatus according to claim 10, further comprising:

means for aborting said switched-out transaction.

16. The apparatus according to claim 10, wherein all other transactions belonging to the same thread as that to which said transaction belongs are allocated to said hardware-based transaction footprint recorder.

17. The apparatus according to claim 10, wherein said hardware-based transaction footprint recorder is a dedicated buffer or a cache associated with one of multiple processor cores.

18. The apparatus according to claim 10, wherein the footprints of said transaction comprise:

memory addresses from which said transaction reads data;

memory addresses to which said transaction writes data; and

data to be written.

19. A computer readable article of manufacture tangibly embodying computer readable instructions for executing a computer implemented method for implementing transaction memory, the method comprising the steps of:

allocating a hardware-based transaction footprint recorder to a transaction for recording footprints of said transaction when the transaction is begun;

determining that said transaction is to be switched out; and

switching out said transaction;

wherein the footprints of said switched-out transaction are kept in said hardware-based transaction footprint recorder.

20. A computer readable article of manufacture according to claim 19, wherein said hardware-based transaction footprint recorder is allocated to multiple transactions simultaneously by incorporating a color bit for identifying to which transaction the footprints belong in each entry of footprints of a transaction.