Liam: An Actor Based Programming Model for HDLs Haven Skinner Rafael Trapani Possignolo Jose Renau Dept. of Computer Engineering Dept. of Computer Engineering Dept. of Computer Engineering
[email protected] [email protected] [email protected] ABSTRACT frequency being locked down early in the development process, The traditional model for developing synthesizable digital architec- and adds a high cost in effort and man-hours, to make high-level tures is a clock-synchronous pipeline. Latency-insensitive systems changes to the system. Although these challenges can be managed, are an alternative, where communication between blocks is viewed they represent fundamental obstacles to developing large-scale as message passing. In hardware this is generally managed by con- systems. trol bits such as valid/stop signals or token credit mechanisms. An alternative is a latency-insensitive design, where the system Although prior work has shown that there are numerous benefits is abstractly seen as being comprised of nodes, which communicate to building latency-insensitive digital hardware, a major factor dis- via messages. Synchronous hardware systems can be automatically couraging its use is the difficulty of managing the additional logic transformed to latency-insensitive designs, which we refer to as and infrastructure required to implement it. elastic systems [1–3]. Alternately, the designer can manually con- We propose a new programming paradigm for Hardware Descrip- trol the latency-insensitive backend [4, 5], we call such systems tion Languages, built on the Actor Model, to implicitly implement Fluid Pipelines. The advantage of exposing the elasticity to the latency-insensitive hardware designs. We call this model Liam, for designer is an increase in performance and flexibility in transforma- Latency-Insensitive Actor-based programming Model.