Simultaneous multithreading
The IBM POWER5, announced in May 2004, comes as either a dual core DCM, or quad-core or 8-core MCM, with each core including a two-thread SMT engine. IBM's implementation is more sophisticated than the previous ones, because it can assign a different priority to the various threads, is more fine-grained, and the SMT engine can be turned on and off dynamically, to better execute those workloads where an SMT processor would not increase performance. This is IBM's second implementation of generally available hardware multithreading.