System and method for reducing serialization in transactional memory using gang release of blocked threads

摘要

Transactional Lock Elision (TLE) may allow multiple threads to concurrently execute critical sections as speculative transactions. Transactions may abort due to various reasons. To avoid starvation, transactions may revert to execution using mutual exclusion when transactional execution fails. Because threads may revert to mutual exclusion in response to the mutual exclusion of other threads, a positive feedback loop may form in times of high congestion, causing a “lemming effect”. To regain the benefits of concurrent transactional execution, the system may allow one or more threads awaiting a given lock to be released from the wait queue and instead attempt transactional execution. A gang release may allow a subset of waiting threads to be released simultaneously. The subset may be chosen dependent on the number of waiting threads, historical abort relationships between threads, analysis of transactions of each thread, sensitivity of each thread to abort, and/or other thread-local or global criteria.