Actors with stretchable access patterns

Abstract

In this article, we propose a new framework based on dataflow graphs to abstract and analyze designs for hard-ware architectures. It is called Actors with Stretchable Access Patterns (ASAP). It can overcome some limitations of all Static Data Flow (SDF) based models like mandatory buffering between actors. This article details the fundamental contributions of ASAP. Firstly, it gives the definition of actors and their different patterns. It also illustrates the link between these notions and components written in VHDL through several examples. Secondly, it presents the main algorithms to check if a graph processes an input data stream correctly, which is called compatibility checking. Thirdly, it summarizes the principles of graph modification to enforce this correctness in case of some blocks are declared incompatible. Finally, it briefly describes our EDA tool called BlAsT which integrates the above principles, before presenting an application on a realistic FPGA design. It shows that ASAP overwhelms other models in terms of resources saving without any impact on the global latency. It also points out the ability of BlAsT to compute and to propose graph modifications and to generate the VHDL code of the whole design.

Automated Buffer Sizing of Dataflow Applications in a High-level Synthesis Workflow

“…SDF-AP is close to CSDF for which optimal buffer sizing methods exist [21,39]; however, such generic methods do not handle the specificity of FPGA such as Equation (2) in our case. SDF-AP too does not match perfectly with FPGA implementations and has been refined to handle stalls and direct token consumption [13], still facing the same complexity and poor scalability. SDF-AP has also been used in the generation of HLS code from templated Haskell [15]; this work is limited by the access patterns required as an input from the user.…”

High-Level Synthesis of Digital Circuits from Template Haskell and SDF-AP

“…SDF-AP also has its shortcomings, which are explained in [6,7] and a solution is introduced, called Static Data-Flow with Actors with Stretchable Access Patterns (SDF-ASAP), in which consumption patterns do not form a minimum requirement, but rather a maximum consumption pattern from which the real execution may be a stretched version. Additional computation patterns are introduced to further specify the relation between tokens on the production and the consumption of a node.…”