Xavier Guerin

Simulink-based MPSoC design flow: case study of Motion-JPEG and H.264

System-level design methodologies have been introduced as a solution to handle the design complexity of embedded multiprocessor SoC (MPSoC) systems. In this paper we describe a system-level design flow starting from Simulink specification, focusing on concurrent hardware and software design and verification at four different abstraction levels: Simulink Combined Algorithm and Architecture Model (CAAM), Virtual Architecture, Transaction-accurate Model and Virtual Prototype. We used two multimedia applications, Motion-JPEG and H.264, to evaluate this design flow. Experimental results show that our design flow can generate various MPSoC architectures from Simulink CAAM correctly and efficiently, allowing processor and task design space exploration at different abstraction levels.

Platform-based software design flow for heterogeneous MPSoC

Current multimedia applications demand complex heterogeneous multiprocessor architectures with specific communication infrastructure in order to achieve the required performances. Programming these architectures usually results in writing separate low-level code for the different processors (DSP, microcontroller), implying late global validation of the overall application with the hardware platform. We propose a platform-based software design flow able to efficiently use the resources of the architecture and allowing easy experimentation of several mappings of the application onto the platform resources. We use a high-level environment to capture both application and architecture initial representations. An executable software stack is generated automatically for each processor from the initial model. The software generation and validation is performed gradually corresponding to different software abstraction levels. Specific software development platforms (abstract models of the architecture) are generated and used to allow debugging of the different software components with explicit hardware-software interaction. We applied this approach on a multimedia platform, involving a high performance DSP and a RISC processor, to explore communication architecture and generate an efficient executable code for a multimedia application. Based on automatic tools, the proposed flow increases productivity and preserves design quality.

Buffer memory optimization for video codec application modeled in Simulink

Reduction of the on-chip memory size is a key issue in video codec system design. Because video codec applications involve complex algorithms that are both data-intensive and control-dependent, memory optimization based on global and precise analysis of data and control dependency is required. We generate a memory-efficient C code from a restricted Simulink model, which can represent both data and control dependency explicitly, by applying two buffer memory optimization techniques: copy removal and buffer sharing. Copy removal is performed while parsing the Simulink model. Buffer sharing requires global scheduling and formal lifetime analysis. Experimental results on an H.264 video decoder show that the buffer memory size and execution time of the C code generated by the proposed method are 71% and 32% less than those of the C code produced by Simulinks C code generator, respectively. When compared to the hand written C code, the memory size was reduced by 27% while its execution time was increased by only 3%

Simulink ® -based heterogeneous multiprocessor SoC design flow for mixed hardware/software refinement and simulation

As a solution for dealing with the design complexity of multiprocessor SoC architectures, we present a joint Simulink-SystemC design flow that enables mixed hardware/software refinement and simulation in the early design process. First, we introduce the Simulink combined algorithm/architecture model (CAAM) unifying the algorithm and the abstract target architecture. From the Simulink CAAM, a hardware architecture generator produces architecture models at three different abstract levels, enabling a trade-off between simulation time and accuracy. A multithread code generator produces memory-efficient multithreaded programs to be executed on the architecture models. To show the applicability of the proposed design flow, we present experimental results on two real video applications.

Efficient Software Development Platforms for Multimedia Applications at Different Abstraction Levels

Multimedia applications require heterogeneous multiprocessor architectures with specific I/O components in order to achieve computation and communication performances. The different processors run different software stacks made of the application code and the hardware dependent software layer. Developing this software usually makes use of a high level programming environment that does not handle specific architecture capabilities. We propose abstract software development platforms allowing to debug incrementally the different software layers and able to accurately estimate the use of the resources of the architecture. The software development platform is an abstract model of the architecture allowing to execute the software with detailed hardware-software interaction, performance measurement and software debug. Different software development platforms are generated automatically from an initial Simulink model and are used to debug the different software components and to easily experiment with several mappings of the application onto the platform resources. In this paper we apply the proposed approach on a multimedia platform, involving a high performance DSP and a RISC processor, to validate the executable code for a MJPEG decoder application.

Reducing fine-grain communication overhead in multithread code generation for heterogeneous MPSoC

Heterogeneous MPSoCs present unique opportunities for emerging embedded applications, which require both high-performance and programmability. Although, software programming for these MPSoC architectures requires tedious and error-prone tasks, thereby automatic code generation tools are required. A code generation method based on fine-grain specification can provide more design space and optimization opportunities, such as exploiting fine-level parallelism and more efficient partitions. However, when partitioned, fine-grain models may require a large number of inter-processor communications, decreasing the overall system performance. This paper presents a Simulink-based multithread code generation method, which applies Message Aggregation optimization technique to reduce the number of inter-processor communications. This technique reduces the communication overheads in terms of execution time by reduction on the number of messages exchanged and in terms of memory size by the reduction on the number of channels. The paper also presents experiment results for one multimedia application, showing performance improvements and memory reduction obtained with Message Aggregation technique.

Synthesis of Communication Mechanisms for Multi-tile Systems Based on Heterogeneous Multi-processor System-On-Chips

Current multimedia applications give birth to a largenumber of complex heterogeneous multiprocessor architectureswith specific communication infrastructure designedto achieve their demanding requirements.To obtain higher computational power with theseMulti-Processor System on Chips (MPSoCs), it is possibleto connect several of them together through a specificnetwork fabric, supported by dedicated NetworkProcessors, reaching complexity levels too high for thegeneral application programmer to cope with. This paperdescribes a flexible and efficient software implementationof communication mechanisms for such architectures,which masks the complexity of the communicationinfrastructure to the application programmer.