Abstract: An apparatus and method for improving the efficiency with which speculative critical sections are executed within a transactional memory architecture. For example, a method in accordance with one embodiment comprises: waiting to execute a speculative critical section of program code until a lock is freed by a current transaction; responsively executing the speculative critical section to completion upon detecting that the lock has been freed, regardless of whether the lock is held by another transaction during the execution of the speculative critical section; once execution of the speculative critical section is complete, determining whether the lock is taken; and if the lock is not taken, then committing the speculative critical section and, if the lock is taken, then aborting the speculative critical section.

Abstract: NUMA-aware reader-writer locks may leverage lock cohorting techniques to band together writer requests from a single NUMA node. The locks may relax the order in which the lock schedules the execution of critical sections of code by reader threads and writer threads, allowing lock ownership to remain resident on a single NUMA node for long periods, while also taking advantage of parallelism between reader threads. Threads may contend on node-level structures to get permission to acquire a globally shared reader-writer lock. Writer threads may follow a lock cohorting strategy of passing ownership of the lock in write mode from one thread to a cohort writer thread without releasing the shared lock, while reader threads from multiple NUMA nodes may simultaneously acquire the shared lock in read mode. The reader-writer lock may follow a writer-preference policy, a reader-preference policy or a hybrid policy.

Abstract: NUMA-aware reader-writer locks may leverage lock cohorting techniques to band together writer requests from a single NUMA node. The locks may relax the order in which the lock schedules the execution of critical sections of code by reader threads and writer threads, allowing lock ownership to remain resident on a single NUMA node for long periods, while also taking advantage of parallelism between reader threads. Threads may contend on node-level structures to get permission to acquire a globally shared reader-writer lock. Writer threads may follow a lock cohorting strategy of passing ownership of the lock in write mode from one thread to a cohort writer thread without releasing the shared lock, while reader threads from multiple NUMA nodes may simultaneously acquire the shared lock in read mode. The reader-writer lock may follow a writer-preference policy, a reader-preference policy or a hybrid policy.