Jianjiang Ceng

MAPS: an integrated framework for MPSoC application parallelization

In the past few years, MPSoC has become the most popular solution for embedded computing. However, the challenge of programming MPSoCs also comes as the biggest side-effect of the solution. Especially, when designers have to face the legacy C code accumulated through the years, the tool support is mostly unsatisfactory. In this paper, we propose an integrated framework, MAPS, which aims at parallelizing C applications for MPSoC platforms. It extracts coarse-grained parallelism on a novel granularity level. A set of tools have been developed for the framework. We will introduce the major components and their functionalities. Two case studies will be given, which demonstrate the use of MAPS on two different kinds of applications. In both cases the proposed framework helps the programmer to extract parallelism efficiently.

An Integrated Open Framework for Heterogeneous MPSoC Design Space Exploration

In recent years, increasing manufacturing density has allowed the development of multi-processor systems-on-chip (MPSoCs). Application-specific instruction set processors (ASIPs) stand out as one of the most efficient design paradigms and could be especially effective as SoC computing engines. However, multiple hurdles which are hindering the productivity of SoC designers and researchers must be solved first. Among them, the difficulty of thoroughly exploring the design space by simultaneously sweeping axes like processing elements, memory hierarchies and chip interconnect fabrics. We tackle this challenge by proposing an integrated approach where state-of-the-art platform modeling infrastructures, at the IP core level and at the system level, meet to provide the designer with maximum openness and flexibility in terms of design space exploration

A high-level virtual platform for early MPSoC software development

Multiprocessor System-on-Chips (MPSoCs) are nowadays widely used, but the problem of their software development persists to be one of the biggest challenges for developers. Virtual Platforms (VPs) are introduced to the industry, which allow MPSoC software development without a hardware prototype. Nevertheless, for developers in early design stage where no VP is available, the software programming support is not satisfactory. This paper introduces a High-level Virtual Platform (HVP) which aims at early MPSoC software development. The framework provides a set of tools for abstract MPSoC simulation and the corresponding application programming support in order to enable the development of reusable C code at a high level. The case study performed on several MPSoCs shows that the code developed on the HVP can be easily reused on different target platforms. Moreover, the high simulation speed achieved by the HVP also improves the design efficiency of software developers.

Trace-based KPN composability analysis for mapping simultaneous applications to MPSoC platforms

Nowadays, most embedded devices need to support multiple applications running concurrently. In contrast to desktop computing, very often the set of applications is known at design time and the designer needs to assure that critical applications meet their constraints in every possible use-case. In order to do this, all possible use-cases, i.e. subset of applications running simultaneously, have to be verified thoroughly. An approach to reduce the verification effort, is to perform composability analysis which has been studied for sets of applications modeled as Synchronous Dataflow Graphs. In this paper we introduce a framework that supports a more general parallel programming model based on the Kahn Process Networks Model of Computation and integrates a complete MPSoC programming environment that includes: compiler-centric analysis, performance estimation, simulation as well as mapping and scheduling of multiple applications. In our solution, composability analysis is performed on parallel traces obtained by instrumenting the application code. A case study performed on three typical embedded applications, JPEG, GSM and MPEG-2, proved the applicability of our approach.

C Compiler Retargeting Based on Instruction Semantics Models

Efficient architecture exploration and design of application specific instruction-set processors (ASIPs) requires retargetable software development tools, in particular C compilers that can be quickly adapted to new architectures. A widespread approach is to model the target architecture in a dedicated architecture description language (ADL) and to generate the tools automatically from the ADL specification. For C compiler generation, however, most existing systems are limited either by the manual retargeting effort or by redundancies in the ADL models that lead to potential inconsistencies. We present a new approach to retargetable compilation, based on the LISA 2.0 ADL with instruction semantics, that minimizes redundancies while simultaneously achieving a high degree of automation. The key of our approach is to generate the mapping rules needed in the compilers code selector from the instruction semantics information. We describe the required analysis and generation techniques, and present experimental results for several embedded processors.

TotalProf: a fast and accurate retargetable source code profiler

Profilers play an important role in software/hardware design, optimization, and verification. Various approaches have been proposed to implement profilers. The most widespread approach adopted in the embedded domain is Instruction Set Simulation (ISS) based profiling, which provides uncompromised accuracy but limited execution speed. Source code profilers, on the contrary, are fast but less accurate. This paper introduces TotalProf, a fast and accurate source code cross profiler that estimates the performance of an application from three aspects: First, code optimization and a novel virtual compiler backend are employed to resemble the course of target compilation. Second, an optimistic static scheduler is introduced to estimate the behavior of the target processors datapath. Last but not least, dynamic events, such as cache misses, bus contention and branch prediction failures, are simulated at runtime. With an abstract architecture description, the tool can be easily retargeted in a performance characteristics oriented way to estimate different processor architectures, including DSPs and VLIW machines. Multiple instances of TotalProf can be integrated with SystemC to support heterogeneous Multi-Processor System-on-Chip (MPSoC) profiling. With only about a 5 to 15% error rate introduced to the major performance metrics, such as cycle count, memory accesses and cache misses, a more than one Giga-Instruction-Per-Second (GIPS) execution speed is achieved.

ASIP architecture exploration for efficient IPSec encryption: A case study

Application-Specific Instruction-Set Processors (ASIPs) are becoming increasingly popular in the world of customized, application-driven System-on-Chip (SoC) designs. Efficient ASIP design requires an iterative architecture exploration loop---gradual refinement of the processor architecture starting from an initial template. To accomplish this task, design automation tools are used to detect bottlenecks in embedded applications, to implement application-specific processor instructions, and to automatically generate the required software tools (such as instruction-set simulator, C-compiler, assembler, and profiler), as well as to synthesize the hardware. This paper describes an architecture exploration loop for an ASIP coprocessor that implements common encryption functionality used in symmetric block cipher algorithms for internet protocol security (IPSec). The coprocessor is accessed via shared memory and, as a consequence, our approach is easily adaptable to arbitrary main processor architectures. This paper presents the extended version of our case study that has been already published on the SCOPES conference in 2004. In both papers, a MIPS architecture is used as the main processor and Blowfish as encryption algorithm.

ASIP Architecture Exploration for Efficient Ipsec Encryption: A Case Study

Application Specific Instruction Processors (ASIPs) are increasingly becoming popular in the world of customized, application-driven System-on-Chip (SoC) designs. Efficient ASIP design requires an iterative architecture exploration loop-gradual refinement of processor architecture starting from an initial template. To accomplish this task, design automation tools are used to detect bottlenecks in embedded applications, to implement application-specific instructions and to automatically generate the required software tools (such as instruction set simulator, C-compiler, assembler, profiler etc.) as well as to synthesize the hardware. This paper describes an architecture exploration loop for an ASIP coprocessor which implements common encryption functionality used in symmetric block cipher algorithms for IPsec. The coprocessor is accessed via shared memory and as a consequence, our approach is easily adaptable to arbitrary processor architectures. In the case study, we used Blowfish as encryption algorithm and a MIPS architecture as main processor.

Modeling Instruction Semantics in ADL Processor Descriptions for C Compiler Retargeting

Today’s Application Specific Instruction-set Processor (ASIP) design methodology often employs centralized Architecture Description Language (ADL) processor models, from which software tools, such as C compiler, assembler, linker, and instruction-set simulator, can be automatically generated. Among these tools, the C compiler is becoming more and more important. However, the generation of C compilers requires high-level architecture information rather than low-level details needed by simulator generation. This makes it particularly difficult to include different aspects of the target architecture into one single model, and meanwhile keeping consistency.