Stochastic Modeling and Performance Analysis of Multimedia SoCs

International audienceQuality of video and audio output is a design-time constraint for portable multimedia devices. Unfortunately, there is a huge cost (e.g. buffer size) incurred to deterministically guarantee good playout quality; the worst-case workload and the timing behavior can be significantly larger than the average-case due to high variability in a multimedia system. In future mobile devices, the playout buffer size is expected to increase, so, buffer dimensioning will remain as an important problem in system design. We propose a probabilistic analytical framework that enables low-cost system design and provides bounds for playing acceptable multimedia quality. We compare our approach with a framework comprising both simulation and statistical model checking, built to simulate large embedded systems in detail. Our results show significant reduction in output buffer size compared to deterministic frameworks

A Compilation Flow for Parametric Dataflow: Programming Model, Scheduling, and Application to Heterogeneous MPSoC

International audienceEfficient programming of signal processing applications on embedded systems is a complex problem. High level models such as Synchronous dataflow (SDF) have been privileged candidates for dealing with this complexity. These models permit to express inherent application parallelism, as well as analysis for both verification and optimization. Parametric dataflow models aim at providing sufficient dynamicity to model new applications, while at the same time maintaining the high level of analyzability needed for efficient real life implementations. This paper presents a new compilation flow that targets parametric dataflows. Built on the LLVM compiler infrastructure, it offers an actor based C++ programming model to describe parametric graphs, a compilation front-end providing graph analysis features, and a retargetable back-end to map the application on real hardware. This paper gives an overview of this flow, with a specific focus on scheduling. The crucial gap between dataflow models and real hardware on which actor firing is not atomic, as well as the consequences on FIFOs sizing and execution pipelining are taken into account.The experimental results illustrate our compilation flow applied to compilation of 3GPP LTE-Advanced demodulation on a heterogeneous MPSoC with distributed scheduling features. This achieves performances similar to time-consuming hand made optimizations

Models for Co-Design of Heterogeneous Dynamically Reconfigurable SoCs

International audienceThe design of Systems-on-Chip is becoming an increasing difficult challenge due to the continuous exponential evolution of the targeted complex architectures and applications. Thus, seamless methodologies and tools are required to resolve the SoC design issues. This chapter presents a high level component based approach for expressing system reconfigurability in SoC co-design. A generic model of reactive control is presented for Gaspard2, a SoC co-design framework. Control integration in different levels of the framework is explored along with a comparison of their advantages and disadvantages. Afterwards, control integration at another high abstraction level is investigated which proves to be more beneficial then the other alternatives. This integration allows to integrate reconfigurability features in modern SoCs. Finally a case study is presented for validation purposes. The presented works are based on Model-Driven Engineering (MDE) and UML MARTE profile for modeling and analysis of real-time embedded systems

System-on-chip Computing and Interconnection Architectures for Telecommunications and Signal Processing

This dissertation proposes novel architectures and design techniques targeting SoC building blocks for telecommunications and signal processing applications. Hardware implementation of Low-Density Parity-Check decoders is approached at both the algorithmic and the architecture level. Low-Density Parity-Check codes are a promising coding scheme for future communication standards due to their outstanding error correction performance. This work proposes a methodology for analyzing effects of finite precision arithmetic on error correction performance and hardware complexity. The methodology is throughout employed for co-designing the decoder. First, a low-complexity check node based on the P-output decoding principle is designed and characterized on a CMOS standard-cells library. Results demonstrate implementation loss below 0.2 dB down to BER of 10^{-8} and a saving in complexity up to 59% with respect to other works in recent literature. High-throughput and low-latency issues are addressed with modified single-phase decoding schedules. A new "memory-aware" schedule is proposed requiring down to 20% of memory with respect to the traditional two-phase flooding decoding. Additionally, throughput is doubled and logic complexity reduced of 12%. These advantages are traded-off with error correction performance, thus making the solution attractive only for long codes, as those adopted in the DVB-S2 standard. The "layered decoding" principle is extended to those codes not specifically conceived for this technique. Proposed architectures exhibit complexity savings in the order of 40% for both area and power consumption figures, while implementation loss is smaller than 0.05 dB. Most modern communication standards employ Orthogonal Frequency Division Multiplexing as part of their physical layer. The core of OFDM is the Fast Fourier Transform and its inverse in charge of symbols (de)modulation. Requirements on throughput and energy efficiency call for FFT hardware implementation, while ubiquity of FFT suggests the design of parametric, re-configurable and re-usable IP hardware macrocells. In this context, this thesis describes an FFT/IFFT core compiler particularly suited for implementation of OFDM communication systems. The tool employs an accuracy-driven configuration engine which automatically profiles the internal arithmetic and generates a core with minimum operands bit-width and thus minimum circuit complexity. The engine performs a closed-loop optimization over three different internal arithmetic models (fixed-point, block floating-point and convergent block floating-point) using the numerical accuracy budget given by the user as a reference point. The flexibility and re-usability of the proposed macrocell are illustrated through several case studies which encompass all current state-of-the-art OFDM communications standards (WLAN, WMAN, xDSL, DVB-T/H, DAB and UWB). Implementations results are presented for two deep sub-micron standard-cells libraries (65 and 90 nm) and commercially available FPGA devices. Compared with other FFT core compilers, the proposed environment produces macrocells with lower circuit complexity and same system level performance (throughput, transform size and numerical accuracy). The final part of this dissertation focuses on the Network-on-Chip design paradigm whose goal is building scalable communication infrastructures connecting hundreds of core. A low-complexity link architecture for mesochronous on-chip communication is discussed. The link enables skew constraint looseness in the clock tree synthesis, frequency speed-up, power consumption reduction and faster back-end turnarounds. The proposed architecture reaches a maximum clock frequency of 1 GHz on 65 nm low-leakage CMOS standard-cells library. In a complex test case with a full-blown NoC infrastructure, the link overhead is only 3% of chip area and 0.5% of leakage power consumption. Finally, a new methodology, named metacoding, is proposed. Metacoding generates correct-by-construction technology independent RTL codebases for NoC building blocks. The RTL coding phase is abstracted and modeled with an Object Oriented framework, integrated within a commercial tool for IP packaging (Synopsys CoreTools suite). Compared with traditional coding styles based on pre-processor directives, metacoding produces 65% smaller codebases and reduces the configurations to verify up to three orders of magnitude

From MARTE to Reconfigurable NoCs: A model driven design methodology

Due to the continuous exponential rise in SoC's design complexity, there is a critical need to find new seamless methodologies and tools to handle the SoC co-design aspects. We address this issue and propose a novel SoC co-design methodology based on Model Driven Engineering and the MARTE (Modeling and Analysis of Real-Time and Embedded Systems) standard proposed by Object Management Group, to raise the design abstraction levels. Extensions of this standard have enabled us to move from high level specifications to execution platforms such as reconfigurable FPGAs. In this paper, we present a high level modeling approach that targets modern Network on Chips systems. The overall objective: to perform system modeling at a high abstraction level expressed in Unified Modeling Language (UML); and afterwards, transform these high level models into detailed enriched lower level models in order to automatically generate the necessary code for final FPGA synthesis

EPICURE: A partitioning and co-design framework for reconfigurable computing

This paper presents a new design methodology able to bridge the gap between an abstract specification and a heterogeneous reconfigurable architecture. The EPICURE contribution is the result of a joint study on abstraction/refinement methods and a smart reconfigurable architecture within the formal Esterel design tools suite. The original points of this work are: (i) a generic HW/SW interface model, (ii) a specification methodology that handles the control, and includes efficient verification and HW/SW synthesis capabilities, (iii) a method for parallelism exploration based on abstract resources/performance estimation expressed in terms of area/delay tradeoffs, (iv) a HW/SW partitioning approach that refines the specification into explicit HW configurations and the associated SW control. The EPICURE framework shows how a cooperation of complementary methodologies and CAD tools associated with a relevant architecture can signficantly improve the designer productivity, especially in the context of reconfigurable architectures

An Infrastructural IP for Interactive MPEG-4 SoC Functional Verification

This paper introduces a specific architecture including an infrastructural IP for functional verification and diagnostics, which is suitable for functional core-based testing of an MPEG4 SoC. Our advanced MPEG4 SoC results in a high complexity SoC with limited physical access to many different functional cores. The proposed test method provides direct monitoring and control for each core, which enables core verification at actual speed. It significantly decreases the verification time due to the large number of required test vectors in typical MPEG4 verification. Furthermore, it also makes the system scalable for functional core expansion due to upgrading of standards. The proposed infrastructural IP is also linked to PC-based interactive tools to simplify the verification of individual and integrated cores. It also provides detailed diagnostic data that enables simple system debugging. The debugging tools also feature test-pattern generation and simulation of expected values. Actual system implementation has shown full functionality of our proposed method

Enhanced TACIT Encryption and Decryption Algorithm for Secured Data Routing in 3-D Network-on-Chip based Interconnection of SoC for IoT Application

520-527This paper presents an enhanced TACIT (E-TACIT) encryption and decryption routing technique. It protects from illegal extraction of secret data in three-dimensional (3−D) routers of Network-on-Chip (NoC) by generating HASH function-based key. The E-TACIT technique solves keys and blocks size limitation of existing anticipated methods, as it has been designed for ‘n’ bit key and ‘n’ block size. Therefore, it secures data while routing process in 3−D NoC based interconnected System-on-chips (SoCs) for Internet-of-Thing (IoT) application. The NoC based interconnection provides high scalability and requires low energy consumption for data processing than conventional bus-based SoCs. The E-TACIT has been examined for Moving Picture Experts Group (MPEG-4). The technique synthesized using Vivado 2016.2 and implemented on ZYNQ XC7Z020-CLG484 FPGA for 1024 bits and verified using a network simulator. Here, we have also incorporated pipelining, re-trimming, and clock gating techniques in the design and used Dual-Port RAM during verification, which helps in achieving low latency and high throughput and occupy less silicon in comparison to Data Encryption Standard (DES) and Advanced Encryption Standard (AES) techniques