Mitsubishi Electric Research Laboratories

Speculative computing is a technique to improve the execution time of certain applications by starting some computations before it is known that the computations are required. A speculative computation will eventually become mandatory (i.e. required) or irrelevant (i.e. not required). In the absence of side effects irrelevant computations may be aborted. However, with side effects a computation which is irrelevant for the value it produces may still be relevant for the side effects it performs. One problem that can result is the relevant synchronization problem wherein one computation requires some side effect event (a "relevant synchronization") to be performed by another computation, which might be aborted, before the first computation can make progress