The classic reason quoted for SMT is to allow the functional units to be fully utilised when there is instruction-to-instruction dependencies - that is, the inp

The classic reason quoted for SMT is to allow the functional units to be fully utilised when there is instruction-to-instruction dependencies - that is, the input of one instruction is the output from the previous instruction. Doing SMT allow you to create one large pool of functional units and share them between multiple threads, hopefully increasing the chances that they will be fully used.