Rosilde Corvino

ASAM: Automatic architecture synthesis and application mapping

This paper focuses on mastering the automatic architecture synthesis and application mapping for heterogeneous massively-parallel MPSoCs based on customizable application-specific instruction-set processors (ASIPs). It presents an overview of the research being currently performed in the scope of the European project ASAM of the ARTEMIS program. The paper briefly presents the results of our analysis of the main challenges to be faced in the design of such heterogeneous MPSoCs. It explains which system, design, and electronic design automation (EDA) concepts seem to be adequate to address the challenges and solve the problems. Finally, it discusses the ASAM design-flow, its main stages and tools and their application to a real-life case study.

ASAM: Automatic Architecture Synthesis and Application Mapping

This paper focuses on mastering the automatic architecture synthesis and application mapping for heterogeneous massively-parallel MPSoCs based on customizable application-specific instruction-set processors (ASIPs). It presents an over-view of the research being currently performed in the scope of the European project ASAM of the ARTEMIS program. The paper briefly presents the results of our analysis of the main problems to be solved and challenges to be faced in the design of such heterogeneous MPSoCs. It explains which system, design, and electronic design automation (EDA) concepts seem to be adequate to resolve the problems and address the challenges. Finally, it introduces and briefly discusses the ASAM design-flow and its main stages.

Exploring processor parallelism: Estimation methods and optimization strategies

Former research on automatic exploration of ASIP architectures mostly focused on either the internal memory hierarchy, or the addition of complex custom operations to RISC based architectures. This paper focuses on VLIW architectures and, more specifically, on automating the selection of an application specific VLIW issue-width. An accurate and efficient issue-width estimation strongly influences all the important processor properties (e.g. processing speed, silicon area, and power consumption). We first compare different methods for estimating the required issue-width, and subsequently introduce a new force-based parallelism measure which is capable of estimating the required issue-width within 3% on average. Moreover, we show that we can quickly estimate the latency-parallelism Pareto-front of an example ECG application with less than 10% error using our issue-width estimations.

Instruction-set architecture exploration strategies for deeply clustered VLIW ASIPs

Instruction-set architecture exploration for clustered VLIW processors is a very complex problem. Most of the existing exploration methods are hand-crafted and time consuming. This paper presents and compares several methods for automating this exploration. We propose and discuss a two-phase method which can quickly explore many different architectures and experimentally demonstrate that this method is capable of automatically achieving a 50% improvement on the energy-delay product cost of an automatically generated architecture for an ECG detection application and a 1% energy-delay product cost improvement compared to a hand-crafted design.

Construction and exploitation of VLIW ASIPs with heterogeneous vector-widths

Numerous applications in important domains, such as communication and multimedia, show a significant data-level parallelism (DLP). A large part of the DLP is usually exploited through application vectorization and implementation of vector operations in processors executing the applications. While the amount of DLP varies between applications of the same domain or even within a single application, processor architectures usually support a single vector width. This may not be optimal and may cause a substantial energy inefficiency. Therefore, an adequate more sophisticated exploitation of DLP is highly relevant. This paper proposes the use of heterogeneous vector widths and a method to explore the heterogeneous vector widths for VLIW ASIPs. In our context, heterogeneity corresponds to the usage of two or more different vector widths in a single ASIP. After a brief explanation of the target ASIP architecture model, the paper describes the vector-width exploration method and explains the associated design automation tools. Subsequently, experimental results are discussed.

Architecture exploration for efficient data transfer and storage in data-parallel applications

Due to the complexity of modern data parallel applications such as image processing applications, automatic approach to infer suitable and efficient hardware realizations are more and more required. Typically, the optimization of data transfer and storage micro-architecture has a key role for the data parallelism. In this paper, we propose a comprehensive method to explore the mapping of a high-level representation of an application into a customizable hardware accelerator. The highlevel representation is in a language called Array-OL. The customizable architecture uses FIFO queues and double buffering mechanism to mask the latency of data transfers and external memory access. The mapping of a high-level representation onto the given architecture is performed by applying a set of loop transformations in Array-OL. A method based on integer partition is used to reduce the space of explored solutions.

An Efficient Method for Energy Estimation of Application Specific Instruction-Set Processors

Design space exploration for ASIP instruction-set design is a very complex problem, involving a large set of architectural choices. Existing methods are usually handcrafted and time-consuming. In this paper, we propose and investigate a rapid method to estimate the energy consumption of candidate architectures for VLIW ASIP processors. The proposed method avoids the time-consuming simulation of the candidate prototypes, without any loss of accuracy in the predicted energy consumption. We experimentally show the effect of this fast cost evaluation method when used in an automated instruction-set architecture exploration. In our experiments, we compare three different methods for cost estimation and find that we can accurately predict the energy consumption of proposed architectures while avoiding simulation of the complete system.

Transformation-Based Exploration of Data Parallel Architecture for Customizable Hardware: A JPEG Encoder Case Study

In this paper, we present a method for the design of MPSoCs for complex data-intensive applications. This method aims at a blend exploration of the communication, the memory system architecture and the computation resource parallelism. The proposed method is exemplified on a JPEG Encoder case study by describing all the design steps. Our method allows for a JPEG encoder implementation having a throughput increase of 84% and an increase of the achievable FPGA maximum frequency fmax of 64% with an area overhead of 6 with respect to a reference solution. Our method is also assessed with additional explorations of applications from different domains.

Algorithm Parallelism Estimation for Constraining Instruction-Set Synthesis for VLIW Processors

Customization of a (generic) processor to a particular application makes it possible to achieve high performance within a tight energy budget. Most of the published research works on processor customization extend a simple base processor with custom instructions. Only few works have considered a full instruction-set customization for complex highly parallel Very Long Instruction Word (VLIW) architectures. This paper discusses the parallelism estimation for a full instruction-set synthesis for VLIW processors and evaluates four methods to compute the maximum parallelism of a given application. We explain important reasons for computing and using such parallelism bounds, discuss the implementation of several methods, and our experimental research performed to evaluate the efficiency of each method.

Abstract Clocks for the DSE of Data-Intensive Applications on MPSoCs

This paper presents an approach advocating abstract clocks to represent data-intensive applications executed on multiprocessor systems-on-chip (MPSoCs) for facilitating the exploration of large design spaces. By using abstract clocks, the advocated method characterizes applications defined by multiple loop nests, as well as, useful loop transformations that contribute to an efficient application execution. It combines the advantages of optimizations provided by loop transformations and the precision of information on scheduling captured by the abstract clocks. As a result, it favors a rapid, and yet accurate design space exploration (DSE) of data-intensive systems.