Fast and Efficient Reacquisition of Locks for Transactional Memory Systems

• US 20110138135A1
• Filed: 12/09/2009
• Published: 06/09/2011
• Est. Priority Date: 12/09/2009
• Status: Active Grant

• Current Assignee: Oracle America, Inc. (Oracle Corporation)
• Original Assignee: Oracle America, Inc. (Oracle Corporation)
• Inventors: Marathe, Virendra J., Shavit, Nir N., Dice, David
• Granted Patent: US 8,375,175 B2
• Time in Patent Office: Days
• US Class Current: 711/152
• CPC Class Codes: G06F 9/467 Transactional memory G06F9/528 takes precedence

Abstract

A system and method is disclosed for fast lock acquisition and release in a lock-based software transactional memory system. The method includes determining that a group of shared memory areas are likely to be accessed together in one or more atomic memory transactions executed by one or more threads of a computer program in a transactional memory system. In response to determining this, the system associates the group of memory areas with a single software lock that is usable by the transactional memory system to coordinate concurrent transactional access to the group of memory areas by the threads of the computer program. Subsequently, a thread of the program may gain access to a plurality of the memory areas of the group by acquiring the single software lock.

Claims

1. A computer-readable storage medium storing program instructions executable by one or more processors to implement:

determining that a group of shared memory areas are likely to be accessed together in one or more atomic memory transactions executed by one or more threads of a computer program in a transactional memory system;

in response to said determining, associating the group of memory areas with a single software lock, wherein the software lock is usable by the transactional memory system to coordinate concurrent transactional access to the group of memory areas by the threads of the computer program;

a thread of the threads acquiring the single software lock; and

subsequent to said acquiring, the thread accessing one or more of the group of memory areas from within an atomic memory transaction governed by the transactional memory system.

2. The computer-readable storage medium of claim 1, wherein said determining is dependent on an observed dynamic memory access behavior of the one more threads.

3. The computer-readable storage medium of claim 1, wherein said determining is dependent on a static analysis of the computer program.

4. The computer-readable storage medium of claim 1, wherein said determining is dependent on the group of memory areas having been accessed from within a single transaction.

5. The computer-readable storage medium of claim 1, wherein said determining is dependent on the group of memory areas having been accessed from within a transaction initiated from a given location in the computer program.

6. The computer-readable storage medium of claim 1, wherein said determining is dependent on a programmer supplied hint.

7. The computer-readable storage medium of claim 1, wherein each of the memory areas is mapped to a respective lock record, each lock record comprising a forwarding pointer, and wherein said associating comprises modifying a value of the forwarding pointer in one or more of the respective lock records to a value usable to locate the single software lock.

8. The computer-readable storage medium of claim 7, wherein each lock record further comprises a software lock.

9. The computer-readable storage medium of claim 8, wherein the single software lock is chosen from among those contained in the lock records to which the memory areas of the group are already mapped.

10. The computer-readable storage medium of claim 1, wherein the program instructions are further executable to implement:

detecting that two or more of the threads have attempted to concurrently access a member of the group from within respective transactions; and

in response to said detecting, disassociating the member of the group from the single software lock.

11. The computer-readable storage medium of claim 1, wherein the single software lock comprises a read/write lock, wherein the read/write lock can be held concurrently by either (a) multiple ones of the threads for read-only access to the group of memory locations or (b) by one of the threads for write access to the group of memory locations.

12. A computer system, comprising:

one or more processors;

a memory coupled to the one or more processors and storing program instructions executable by the processors to implement a method comprising;

determining that a group of shared memory areas are likely to be accessed together in one or more atomic memory transactions executed by one or more threads of a computer program in a transactional memory system;

in response to said determining, associating the group of memory areas with a single software lock, wherein the software lock is usable by the transactional memory system to coordinate concurrent transactional access to the group of memory areas by the threads of the computer program;

a thread of the threads acquiring the single software lock; and

subsequent to said acquiring, the thread accessing one or more of the group of memory areas from within an atomic memory transaction governed by the transactional memory system.

13. The system of claim 12, wherein said determining is dependent on an observed dynamic memory access behavior of the one more threads.

14. The system of claim 12, wherein said determining is dependent on a static analysis of the computer program.

15. The system of claim 12, wherein said determining is dependent on the group of memory areas having been accessed from within a single transaction.

16. The system of claim 12, wherein each of the memory areas is mapped to a respective lock record, each lock record comprising a forwarding pointer, and wherein said associating comprises modifying a value of the forwarding pointer in one or more of the respective lock records to a value usable to locate the single software lock.

17. The system of claim 16, wherein each lock record further comprises a software lock and wherein the single software lock is chosen from among those contained in the lock records to which the memory areas of the group are already mapped.

18. A computer-implemented method, comprising:

determining that a group of shared memory areas are likely to be accessed together in one or more atomic memory transactions executed by one or more threads of a computer program in a transactional memory system;

in response to said determining, associating the group of memory areas with a single software lock, wherein the software lock is usable by the transactional memory system to coordinate concurrent transactional access to the group of memory areas by the threads of the computer program;

a thread of the threads acquiring the single software lock; and

subsequent to said acquiring, the thread accessing one or more of the group of memory areas from within an atomic memory transaction governed by the transactional memory system.

19. The computer-implemented method of claim 18, wherein said determining is dependent on an observed dynamic memory access behavior of the one more threads.

20. The computer-implemented method of claim 18, wherein said determining is dependent on a static analysis of the computer program.