TRANSACTIONAL MEMORY (TM) simplifies parallel programming by  guaranteeing that transactions appear to execute atomically and in  isolation. Implementing these properties includes providing data  version management for the simultaneous storage of both new (visible  if the transaction commits) and old (retained if the transaction  aborts) values. Most (hardware) TM systems leave old values "in  place" (the target memory address) and buffer new values elsewhere  until commit. This makes aborts fast, but penalizes (the much more  frequent) commits.

In this work, we present a new implementation of transactional  memory, LOG-BASED TRANSACTIONAL MEMORY (LogTM), that makes commits  fast by storing old values to a per-thread log in cacheable virtual  memory and storing new values in place. LogTM makes two additional  contributions. First, LogTM extends a MOESI directory protocol to  enable both fast conflict detection on evicted blocks and fast commit  (using lazy cleanup). Second, LogTM handles aborts in (library)  software with little performance penalty. Evaluations running micro-  and SPLASH-2 benchmarks on a 32-way multiprocessor support our  decision to optimize for commit by showing that only 1-2% of  transactions abort.

C.f. http://www.cs.wisc.edu/multifacet/papers/hpca06_logtm.pdf or the Wisconsin Multifacet

home page (http://www.cs.wisc.edu/multifacet/).

This work done in collaboration with Kevin E. Moore, Jayaram Bobba,  Michelle J. Moravan, and David A. Wood.

Biography
MARK D. HILL (http://www.cs.wisc.edu/~markhill) is professor in both  the computer sciences department and the electrical and computer  engineering department at the University of Wisconsin-Madison, where  he also co-leds the Wisconsin Multifacet (http://www.cs.wisc.edu/ multifacet/) project with David Wood. His research interests include  parallel computer system design, memory system design, and computer  simulation. He earned a PhD from University of California, Berkeley.  He is an ACM Fellow and a Fellow of the IEEE.

Friday, February 3 , 2006

Wu & chen Auditorium

101 Levine Hall

3:00pm - pm