Effective power saving method by on-chip traffic compression in noc-based embedded systems

[EN] of components, relying on an efficient on-chip network (network-on-chip; NoC). As the size of the system increases, NoC performance and power consumption become a central issue. In this project, we design compression strategies at the NoC level reducing the number of transmitted flits and consequently the energy consumed. The provided mechanism relies on the abundance of memory data blocks filled with zeros in the analysed applications, thus easily compressible by using a zero-elimination strategy. We provide a hardware implementation for both compression and decompression end points at a generic network interface (NI). The mechanisms have been designed in isolated mode in order to make them modular and easily adapted to any NI protocol. Results show the effectiveness of the compression and decompression mechanisms and the low overhead they introduce. The percentage of traffic reduced by the compression strategy (it is reduced by a factor of 3) justifies the added resources. This work reflects some parts of the main research directions we tackle in the wider PhD framework. In particular, we propose a method for power efficient memory traffic management. The work presented here represents the initial research directions in simulation development, traffic pattern characterization and initial solutions development[ES] Con los avances de la tecnología, los sistemas en chip multiprocesador (MPSoC) aumentan en número de componentes, apoyándose en una red en el chip (NoC) eficiente. Según crece el tamaño de estos sistemas, la eficiencia de la red tanto temporal como energética se convierte en una parte primordial. En este proyecto diseñamos estrategias de compresión a nivel de red (en la NoC) reduciendo el número de flits transmitidos y por tanto la energía consumida. El método propuesto se basa en la abundancia de bloques de memoria con largas cadenas de ceros que se detectaron en las aplicaciones analizadas. Esta abundancia de ceros facilita la compresión mediante estrategias de eliminación de ceros. Ofrecemos una implementación hardware tanto de la parte de compresión como de la de descompresión sobre un interfaz de red (NI) genérico. Los mecanismos propuestos han sido diseñados de forma aislada para hacerlos modulares y fácilmente adaptables a cualquier protocolo de NI. Los resultados muestran la efectividad de los mecanismos de compresión y descompresión y la escasa penalización que introducen. El porcentaje de tráfico reducido mediante la estrategia de compresión (se reduce con un factor de 3) justifica los recursos extra requeridos. Este trabajo refleja parte de la línea de investigación global que se pretende abordar en el marco más amplio de un doctorado. En particular proponemos un método de gestión del tráfico de memoria energéticamente eficiente. El trabajo presentado aquí representa pues una primera aproximación a la investigación realizando un desarrollo parcial del simulador, caracterización de patrones de tráfico y el desarrollo de una solución parcialSoler Heredia, M. (2013). Effective power saving method by on-chip traffic compression in noc-based embedded systems. http://hdl.handle.net/10251/43774Archivo delegad

Test-Delivery Optimization in Manycore SOCs

We present two test-data delivery optimization algorithms for system-on-chip (SOC) designs with hundreds of cores, where a network-on-chip (NOC) is used as the interconnection fabric. We first present an e ective algorithm based on a subsetsum formulation to solve the test-delivery problem in NOCs with arbitrary topology that use dedicated routing. We further propose an algorithm for the important class of NOCs with grid topology and XY routing. The proposed algorithm is the first to co-optimize the number of access points, access-point locations, pin distribution to access points, and assignment of cores to access points for optimal test resource utilization of such NOCs. Testtime minimization is modeled as an NOC partitioning problem and solved with dynamic programming in polynomial time. Both the proposed methods yield high-quality results and are scalable to large SOCs with many cores. We present results on synthetic grid topology NOC-based SOCs constructed using cores from the ITC’02 benchmark, and demonstrate the scalability of our approach for two SOCs of the future, one with nearly 1,000 cores and the other with 1,600 cores. Test scheduling under power constraints is also incorporated in the optimization framework

Improving the Test of NoC-Based SoCs with Help of Compression Schemes

International audienceRe-using the network in a NoC-based system as a test access mechanism is an attractive solution as pointed out by several authors. As a consequence, testing of NoC-based SoCs is becoming a new challenge for designers. However, the effectiveness of testing methods is highly dependent on the number of test interfaces with the tester. This paper proposes the use of a test data compression scheme to increase the number of test interfaces (thus increasing test parallelism) without increasing the number of required Automated Test Equipment (ATE) channels. We show that the combination of compression and NoC-based test scheduling allows a drastic reduction of the system test time at the expense of a very small area overhead