A Comprehensive Study of Conflict Resolution Policies in Hardware Transactional Memory

The underlying conflict resolution policy plays a vital role in the performance of most Transactional Memory (TM) systems and there is not a commonly accepted policy. Work carried out in this field contains a wide choice of conflict resolution ideas and authors tend to make their choices according to their workload characteristics. The conflict resolution policy is especially critical in eager-versioning, eager-conflict management Hardware Transactional Memory (HTM) implementations since these implementations are typically optimized for commit and therefore assume that conflicts are rare. This paper will make a comprehensive study of conflict resolution policies for eager HTM systems. We will re-visit previously studied policies, as well as proposing new policies to mitigate performance bottleneck scenarios. The policies are then evaluated using the STAMP TM benchmark suite and compared against an HTM baseline that employs an elementary conflict resolution policy. The results indicate that it is possible to achieve performance gains of 15% using carefully designed conflict resolution policies.