Simultaneous Multi-Threading
Simultaneous Multi-Threading (SMT) is the ability of a single physical processor to simultaneously dispatch instructions from more than one hardware thread context. It is a feature of the POWER5 processor and will be available at the same time as shared processors. There are two hardware threads per processor. SMT is designed to take advantage of the superscalar nature of the POWER5 processor, so that more instructions can be executed at the same time. The basic concept is that no single application can fully saturate the processor, so it is better to have multiple applications providing input at the same time.
SMT is expected to be used primarily in environments, where the speed of an individual transaction is not as important as the total number of transactions that can be performed. It is expected to increase the throughput of workloads with large or frequently changing working sets, such WAS.