STM Systems: Enforcing Strong Isolation between Transactions and Non-transactional Code

Transactional memory (TM) systems implement the concept of an atomic execution unit called transaction in order to discharge programmers from explicit synchronization management. But when shared data is atomically accessed by both transaction and non-transactional code, a TM system must provide strong isolation in order to overcome consistency problems. Strong isolation enforces ordering between non-transactional operations and transactions and preserves the atomicity of a transaction even with respect to non-transactional code. This paper presents a TM algorithm that implements strong isolation with the following features: (a) concurrency control of non-transactional operations is not based on locks and is particularly efficient, and (b) any non-transactional read or write operation always terminates (there is no notion of commit/abort associated with them). Key-words: Transactional Memory, Strong Isolation, Atomicity ∗ IRISA, Université de Rennes 35042 Rennes Cedex, France † Institut Universitaire de France ha l-0 06 99 90 3, v er si on 1 21 M ay 2 01 2 Mémoire Transactionnelle: Imposer l’isolement forte entre transactions et opérations non-transactionnelle Résumé : Ce rapport présente un algorithme de mémoire transactionnelle qui impose l’isolement forte entre transactions et opérations non-transactionnelle. Mots-clés : mémoire transactionnelle, atomicité ha l-0 06 99 90 3, v er si on 1 21 M ay 2 01 2 STM systems: Enforcing strong isolation between transactions and non-transactional code 3