The AMD Advanced Synchronization Facility (ASF) is an experimental instruction set extension for the AMD64 architecture that would provide new capabilities for efficient synchronization of access to shared data in highly multithreaded applications as well as operating system kernels. ASF code can also inter-operate with lock-based code, or with Software Transactional Memory.

PTLsim is a near-cycle-accurate AMD64 simulator with in-order and out-of-order execution-core models.

PTLsim-ASF is a version of PTLsim that implements the AMD Advanced Synchronization Facility (ASF) of them AMD64 architecture.

A proper specification of ASF has been proposed, please find the proposal at:
Please find more information on ASF and PTLsim on the following web site:
VELOX Release Download Release Date
Release 3 22.02.2011
Release 2 01.09.2010