This presentation will give an update on the performance evaluation of
the hardware support for transactional memory (TM) on the Blue Gene/Q
(BG/Q) machine. It will describes an end-to-end system implementation
of the TM programming model on top of the hardware transactional memory
(HTM) of the Blue Gene/Q (BG/Q) machine. The TM programming model
supports most C/C++ programming constructs on top of a best-effort HTM
with the help of a complete software stack including the compiler, the
kernel, and the TM runtime.

This extensive evaluation of the STAMP benchmarks on BG/Q is the first
of its kind in understanding characteristics of running coarse-grained
TM workloads on HTMs. The study reveals several interesting insights on
the overhead and the scalability of BG/Q HTM with respect to sequential
execution, coarse-grain locking, and software TM.

A version of this talk will be presented at PACT 2012 in Minneapolis in
September (it has been nominated as one of the three best papers for
PACT 2012). The presentation at CDP will include additional benchmarks
as well as a complete comparative analysis of the performance using
short-running X long-running mode.