  Many concurrent data-structure implementations use the well-known
compare-and-swap (CAS) operation, supported in hardware by most modern
multiprocessor architectures for inter-thread synchronization. A key weakness
of the CAS operation is the degradation in its performance in the presence of
memory contention.
  In this work we study the following question: can software-based contention
management improve the efficiency of hardware-provided CAS operations? Our
performance evaluation establishes that lightweight contention management
support can greatly improve performance under medium and high contention levels
while typically incurring only small overhead when contention is low.
