Scheduling strategies for multiprocessor real-time DSP
IEEE Global Telecommunications Conference, 1989, and Exhibition. 'Communications Technology for the 1990s and Beyond
or in the multiprocessor systems literature. This paper will attempt to define these. Real-time digital signal processing often requires multiple processors. We assume the description of the program to be scheduled is a Unfortunately, in most practical situations, partitioning of DSP applica-dataflow graph, signal flow graph, or block diagram. Language classes tions for execution on multiple programmable Processors is ad-hoc. that are efficiently translated into dataflow graphs include
... l, Automatic schedulers either (1) add unacceptable Cost to the imple-applicative, and single-assignment. In a dataflow graph the nodes, or mentation Or (2) address only a subset of applications. This Paper actors, are functions that operate on data passed through the arcs. The explores the possibilities for automatic schedulers that result in I OW model is data-driven, in that actors fire (or perform their computation), imP1emenQfion Cost and Can target a broad class of DSP applications. when sufficient data is available on their input arcs. The role of the We Can define four classes of scheduling strategies, (1) fully dynamic, scheduler is simply to determine when to fire actors and on which pro-(2) static assiPment, (3) self-timed, and (4) fully static. Moving from cessor. The actors may have arbitrary granularity, meaning that they (1) to (4). more scheduling activity is Performed at compile time and may represent atomic operations, such as addition and multiplication, less at run time. This Paper argues that for most DSP applications, or much more elaborate operations, such as transforms or digital filters. self-timed scheduling is the most attractive. We assume that no attempt will be made to exploit concurrency within an actor, so that the scheduler only needs to operate on the dataflow graph. 35.2.1.