Intel Threading Building Blocks

Notes on parallel_while scaling

Use of parallel_while usually does not provide scalable parallelism if the add method is not used because the input stream typically acts as a bottleneck. However, this bottleneck is broken if the stream is used to get things started and further items come from prior items invoking the add method.

Even in the nonscalable case, parallel_while covers a commonly desired idiom of walking a sequential structure (e.g., a linked list) and dispatching concurrent work for each item in the structure.