Brief Announcement: From Causal to z-Linearizable Transactional Memory Torvald Riegel and Christof Fetzer and Heiko Sturzrehm and Pascal Felber Appeared in: 26th ACM SIGACT-SIGOPS Symposium on Principles of Distributed Computing Date: August 2007 Download: PRESENTATION SLIDES Download: BIBTEX (riegel2007zlin) The current generation of time-based transactional memories (TMs) has the advantage of being simple and efficient, and providing strong linearizability semantics. Linearizability matches well the goal of TM to simplify the design and implementation of concurrent applications. However, long transactions can have a much lower likelihood of committing than smaller transactions because of the strict ordering constraints imposed by linearizability. We investigate the use of weaker semantics for TM and introduce a new consistency criterion that we call z-linearizability. By combining properties of linearizability and serializability, z-linearizability provides a good trade-off between strong semantics and good practical performance even for long transactions.