Francesco Poletti

Communication-aware allocation and scheduling framework for stream-oriented multi-processor systems-on-chip

This paper proposes a complete allocation and scheduling framework, where an MPSoC virtual platform is used to accurately derive input parameters, validate abstract models of system components and assess constraint satisfaction and objective function optimization. The optimizer implements an efficient and exact approach to allocation and scheduling based on problem decomposition. The allocation subproblem is solved through integer programming while the scheduling one through constraint programming. The two solvers can interact by means of no-good generation, thus building an iterative procedure which has been proven to converge to the optimal solution. Experimental results show significant speedups w.r.t. pure IP and CP exact solution strategies as well as high accuracy with respect to cycle accurate functional simulation. A case study further demonstrates the practical viability of our framework for real-life systems and applications

Exploring “temperature-aware” design in low-power MPSoCs

The power density inside high performance systems continues to rise with every process technology generation, thereby increasing the operating temperature and creating “hot spots” on the die. As a result, the performance, reliability and power consumption of the system degrade. To avoid these “hot spots”, “temperature-aware” design has become a must. For low-power embedded systems though, it is not clear whether similar thermal problems occur. These systems have very different characteristics from the high performance ones: they consume hundred times less power, they are based on a multi-processor architecture with lots of embedded memory and rely on cheap packaging solutions. In this paper, we investigate the need for temperature-aware design in a low-power systems-on-a-chip and provide guidlines to delimit the conditions for which temperature aware design is needed.

Combining Simulation and Formal Methods for System-Level Performance Analysis

Recent research on performance analysis for embedded systems shows a trend to formal compositional models and methods. These compositional methods can be used to determine the performance of embedded systems by composing formal analytical models of the individual components. In case there exist no formal component models with the required precision, simulation-based approaches are used for system-level performance analysis. The often high runtimes of simulation runs lead to the new approach described in this paper: Analytical methods are combined with simulation-based approaches to speed up simulation. We describe how the simulation models can be coupled with the formal analysis framework, specify the interfaces needed for such a combination and show the applicability of the approach using a case study

Performance Analysis of Arbitration Policies for SoC Communication Architectures

As technology scales toward deep submicron, the integration of a large number of IP blocks on the same silicon die is becoming technically feasible, thus enabling large-scale parallel computations, such as those required for multimedia workloads. The communication architecture is becoming the bottleneck for these multiprocessor Systems-on-Chip (SoC), and efficient contention resolution schemes for managing simultaneous access requests to the shared communication resources are required to prevent system performance degradation. The contribution of this work is to analyze the impact on multiprocessor SoC performance of different bus arbitration policies under different communication patterns, showing the distinctive features of each policy and the strong correlation of their effectiveness with the communication requirements of the applications. Beyond traditional arbitration schemes such as round robin and TDMA, another policy is considered that periodically allocates a temporal slot for contention-free bus utilization to a processor which needs fixed predictable bandwidth for the correct execution of its time-critical task. The results are derived on a complete and scalable multiprocessor SoC simulation platform based on SystemC, whose software support includes a complete embedded multiprocessor OS (RTEMS). The communication architecture is AMBA compliant, and we exploit the flexibility of this multi-master commercial standard, which does not specify the arbitration algorithm, to implement the explored contention resolution schemes.

A fast HW/SW FPGA-based thermal emulation framework for multi-processor system-on-chip

With the growing complexity in consumer embedded products and the improvements in process technology, multi-processor system-on-chip (MPSoC) architectures have become widespread. These new systems are complex to design as they must execute multiple complex applications (e.g. video processing, 3D games), while meeting additional design constraints (e.g. energy consumption or time-to-market). Moreover, the rise of temperature in the die for MPSoC components can seriously affect their final performance and reliability. Therefore, mechanisms to efficiently evaluate complete HW/SW MPSoC designs in terms of energy consumption, temperature, performance and other key metrics are needed. In this paper, we present a new HW/SW FPGA-based emulation framework that allows designers to rapidly extract a number of critical statistics from processing cores, memories and interconnection systems being emulated on a FPGA. This information is then used to interact in real-time with a SW thermal model running on a host computer via an Ethernet port. The results show speed-ups of three orders of magnitude compared to cycle-accurate MPSoC simulators, which enable a very fast exploration of a large range of MPSoC design alternatives at the cycle-accurate level. Finally, our HW/SW framework allows designers to test run-time thermal management strategies with real-life inputs without any loss in the performance of the emulated system

HW-SW emulation framework for temperature-aware design in MPSoCs

New tendencies envisage multiprocessor systems-on-chips (MPSoCs) as a promising solution for the consumer electronics market. MPSoCs are complex to design, as they must execute multiple applications (games, video) while meeting additional design constraints (energy consumption, time-to-market). Moreover, the rise of temperature in the die for MPSoCs can seriously affect their final performance and reliability. In this article, we present a new hardware-software emulation framework that allows designers a complete exploration of the thermal behavior of final MPSoC designs early in the design flow. The proposed framework uses FPGA emulation as the key element to model hardware components of the considered MPSoC platform at multimegahertz speeds. It automatically extracts detailed system statistics that are used as input to our software thermal library running in a host computer. This library calculates at runtime the temperature of on-chip components, based on the collected statistics from the emulated system and final floorplan of the MPSoC. This enables fast testing of various thermal management techniques. Our results show speedups of three orders of magnitude compared to cycle-accurate MPSoC simulators.

A multiprocessor system-on-chip for real-time biomedical monitoring and analysis: architectural design space exploration

In this paper we focus on MPSoC architectures for human heart ECG real-time monitoring and analysis. This is a very relevant biomedical application, with a huge potential market, hence it is an ideal target for an application-specific SoC implementation. We investigate a symmetric multi-processor architecture based on STMicroelectronics VLIW DSPs that process in real-time 12-lead ECG signals. This architecture improves upon state-of-the-art SoC designs for ECG analysis in its ability to analyze the full 12 leads in real-time, even with high sampling frequencies, and ability to detect heart malfunction. We explore the design space by considering a number of hardware and software architectural options

Energy-Efficient Multiprocessor Systems-on-Chip for Embedded Computing: Exploring Programming Models and Their Architectural Support

In todays multiprocessor SoCs (MPSoCs), parallel programming models are needed to fully exploit hardware capabilities and to achieve the 100 Gops/W energy efficiency target required for ambient intelligence applications. However, mapping abstract programming models onto tightly power-constrained hardware architectures imposes overheads which might seriously compromise performance and energy efficiency. The objective of this work is to perform a comparative analysis of message passing versus shared memory as programming models for single-chip multiprocessor platforms. Our analysis is carried out from a hardware-software viewpoint: we carefully tune hardware architectures and software libraries for each programming model. We analyze representative application kernels from the multimedia domain, and identify application-level parameters that heavily influence performance and energy efficiency. Then, we formulate guidelines for the selection of the most appropriate programming model and its architectural support

Efficient system-level prototyping of power-aware dynamic memory managers for embedded systems

In the near future, portable embedded devices must run multimedia and wireless network applications with enormous computational performance (1-40GOPS) requirements at a low energy consumption (0.1-2W). In these applications, the dynamic memory subsystem is currently one of the main sources of power consumption and its inappropriate management can severely affect the performance of the whole system. Within this context, the construction and power evaluation of custom memory managers is one of the most difficult parts for an efficient mapping of such dynamic applications on low-power embedded systems. In this paper, we present a new system-level approach to model complex dynamic memory managers integrating detailed power profiling information. This approach allows to obtain power consumption estimates, memory footprint and memory access values to refine the dynamic memory management of the system in an early stage of the design flow and to easily explore the large search space of memory manager implementations.

MPSoC ECG biochip: a multiprocessor system-on-chip for real-time human heart monitoring and analysis

The interest in high performance chip architectures for biomedical applications is on the rise. Heart diseases remain by far the main cause of death and a challenging problem for biomedical engineers to monitor and analyze. Electrocardiography (ECG) is an essential practice in heart medicine, which faces computational challenges, especially when 12 lead signals are to be analyzed in parallel, in real time, and under increasing sampling frequencies. Another challenge is the analysis of huge amounts of data that may grow to days of recordings. Nowadays, doctors use eyeball monitoring of the 12-lead ECG paper readout, which may seriously impair analysis accuracy. Our solution leverages the advance in multi-processor system-on-chip architectures, and is centered on the parallelization of the ECG computation kernel. It improves upon state-of-the-art mostly for its capability to perform real-time analysis of input data, leveraging the computation horsepower provided by many concurrent DSPs, more accurate diagnosis of cardiac diseases, and prompter reaction to abnormal heart alterations. The design methodology to go from the 12-lead ECG application specification to the final hardware/software architecture, modeling, and simulation is the focus of this paper. Our system model is based on industrial components. The architectural template we employ is scalable and flexible.