Avoiding locks by transactionally executing critical sections

A method for avoiding locks by transactionally executing critical sections of code, comprising:

• prior to transactionally executing critical sections of code, executing a start transactional execution (STE) instruction;
• allowing a process to transactionally execute a critical section of code within a program without acquiring a lock associated with the critical section;
• wherein transactionally executing the critical section involves first determining if the lock associated with the critical section is held by another process and if so aborting the transactional execution;
• wherein if the process completes the critical section without encountering an interfering data access from another process, the method further comprises,
• committing changes made during the transactional execution, and
• optionally resuming normal non-transactional execution of the program past the critical section;
• and
• wherein if an interfering data access from another process is encountered during transactional execution of the critical section, the method further comprises,
• discarding changes made during the transactional execution, and
• attempting to re-execute the critical section zero or more times;
• wherein the program executes in normal execution mode an alternate block of code that is specified by the STE instruction if the program does not attempt to re-execute the critical section or all attempts to re-execute the critical section fail.

An apparatus that modifies a program to avoid locks by transactionally executing critical sections, comprising:

• a processor configured to modify the program so that critical sections which are protected by locks are executed transactionally without acquiring locks associated with the critical sections;
• wherein the processor is configured to modify the program so that,
• a start transactional execution (STE) instruction is executed before entering the critical section and an instruction is executed before entering the critical section that aborts the transactional execution when it is determined that another thread holds a lock associated with the critical section;
• if the transactional execution of the critical section completes without encountering an interfering data access from another process, the program commits changes made during the transactional execution and optionally resumes normal non-transactional execution of the program past the critical section;
• and
• otherwise, if an interfering data access from another process is encountered during transactional execution of the critical section, the program discards changes made during the transactional execution, and attempts to re-execute the critical section zero or more times;
• wherein the program executes in normal execution mode an alternate block of code that is specified by the STE instruction if the program does not attempt to re-execute the critical section or all attempts to re-execute the critical section fail.