Handling Operating System (Os) Transitions In An Unbounded Transactional Memory (Utm) Mode

At least one computer readable storage medium comprising instructions that when executed enable a system to:

• receive control in a kernel mode via a ring transition from a first user thread during execution of an unbounded transactional memory (UTM) transaction in the first user thread;
• clear at least one UTM property of the UTM transaction, update a state of at least one event field of a transaction status register (TSR) associated with the first user thread to indicate the clear, and store the TSR with a context of the first user thread;
• and
• restore the first user thread context including the TSR to a processor and transition from the kernel mode to the first user thread.

A method comprising:

• executing an unbounded transactional memory (UTM) transaction in a first user thread of a user mode of the system;
• incurring an event during execution of the UTM transaction that causes a transition from the first user thread to a kernel mode, the event comprising an exception;
• suspending but not aborting the UTM transaction before transitioning to the kernel mode;
• updating at least one status field of at least one transaction register of a processor associated with the first user thread in an exception handler of the kernel mode;
• and
• thereafter executing one of a plurality of code paths in the user mode based on execution of the exception handler.