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SUMMARY:Coarse-grained transactions - Eric Koskinen (University of Cambrid
 ge)
DTSTART:20091130T124500Z
DTEND:20091130T140000Z
UID:TALK20703@talks.cam.ac.uk
CONTACT:Sam Staton
DESCRIPTION:Traditional transactional memory systems suffer from overly co
 nservative conflict detection\, yielding so-called false conflicts\, becau
 se they are based on fine-grained\, low-level read/write conflicts. In res
 ponse\, the recent trend has been toward integrating various abstract data
 -type libraries using ad-hoc methods of high-level conflict detection. The
 se proposals have led to improved performance but a lack of a unified theo
 ry has led to confusion\nin the literature.\n\nWe clarify these recent pro
 posals by defining a generalization of transactional memory in which a tra
 nsaction consists of abstract data-type operations rather than simply memo
 ry read/write operations. We provide semantics for both pessimistic (e.g. 
 transactional boosting) and optimistic (e.g. traditional TMs and recent al
 ternatives) execution. We show that both are included in the standard atom
 ic semantics\, yet find that the choice imposes different requirements on 
 the coarse-grained operations: pessimistic requires operations be left-mov
 ers\, optimistic requires right-movers. Finally\, we discuss how the seman
 tics applies to numerous TM implementation details discussed widely in the
  literature.
LOCATION:Room FW26\, Computer Laboratory\, William Gates Building
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