Sharif Digital Repository

Programmable hardware is gaining popularity as it can keep pace with growing performance demand in tight power budget, design and test cost, and serious reliability concerns of future multiprocessor embedded systems. Compatible with this trend, Network-on-Chip, as a potential bottleneck of future multi-cores, should also support pro-grammability. Here, we address this issue in design and implementation of routing algorithm for two-dimensional mesh. To this end, we allocate paths based on input traffic pattern and in parallel with customizing routing restriction for deadlock freedom. To achieve this, we propose extended turn model (ETM), a novel parametric deadlock-free routing for 2D meshes... 

The continuance of Moore's law and failure of Dennard scaling force future chip multiprocessors (CMPs) to have considerable dark regions. How to use up available dark resources is an important concern for computer architects. In harmony with these changes, we must revise processor allocation schemes that severely affect the performance of a parallel on-chip system. A suitable allocation algorithm should reduce runtime and increase the power efficiency with proper thermal distribution to avoid hotspots. With this motivation, this paper proposes a power-efficient and high performance general purpose infrastructure for which a Dark Silicon Aware Processor Allocation (DSAPA) scheme is proposed... 

In this paper, having investigated the behavior of GPGPU applications, we present an effcient L2 cache architecture for GPUs based on STT-RAM technology. With the increase of processing cores count, larger on-chip memories are required. Due to its high density and low power characteristics, STT-RAM technology can be utilized in GPUs where numerous cores leave a limited area for on-chip memory banks. They have however two important issues, high energy and latency of write operations, that have to be addressed. Low data retention time STT-RAMs can reduce the energy and delay of write operations. However, employing STT-RAMs with low retention time in GPUs requires a thorough investigation on... 

Dissolution pressure and nozzle temperature effects on particle size and distribution were investigated for RESS (Rapid Expansion of Supercritical Solution) process. Supercritical CO2 was used as solvent and Ibuprofen was applied as the model component in all runs. The resulting Ibuprofen nano-particles (about 50 nm in optimized runs) were analyzed by SEM and laser diffraction particle size analyzer systems. Results show that in low supercritical pressure ranges, depending on the solvent and solid component properties (Lower than 105 bar for Ibuprofen-CO2 system), nozzle temperature should be as low as possible (80-90 °C for Ibuprofen-CO2 system). In the other hand in high supercritical... 

Network-on-Chip combined with Globally Asynchronous Locally Synchronous paradigm is a promising architecture for easy IP integration and utilization with multiple voltage levels. For power reduction, multiple voltage-frequency levels are successfully applied to 2-D NoCs, but never with a generic approach to 3-D counterparts; in which low heat conductivity of insulator layers makes high dense temperature distribution at layers away from heat sink. In this paper, a thermal-aware methodology for regular 3-D NoCs based on multiple voltage levels is proposed. Given an application task graph, this methodology determines an efficient mapping of tasks onto network tiles, considering inherent... 

End-to-end delay, throughput, energy consumption, and silicon area are the most important design metrics of networks-on-chip (NoCs). Although several analytical models have been previously proposed for predicting such metrics in NoCs, very few of them consider the effect of message waiting time in the buffers of network routers for predicting overall power consumptions and none of them consider structural heterogeneity of network routers. This paper introduces two inter-related analytical models to compute message latency and power consumption of NoCs with arbitrary topology, buffering structure, and routing algorithm. Buffer allocation scheme defines the buffering space for each individual... 

In this paper, we have proposed a new face detection method which combines the AdaBoost algorithm with skin color information and support vector machine (SVM). First, a cascade classifier based on AdaBoost is used to detect faces in images. Due to noise and illumination changes some nonfaces might be detected too, therefore we have used a skin color model in the YCbCr color space to remove some of the detected nonfaces. Finally, we have utilized SVM to detect faces more accurately. Experimental results show that the performance of the proposed method is higher than the basic AdaBoost in the sense of detecting fewer nonfaces  

Network-on-Chip combined with Globally Asynchronous Locally Synchronous paradigm is a promising architecture for easy IP integration and utilization with multiple voltage levels. For power reduction, multiple voltage-frequency levels are successfully applied to 2-D NoCs, but never with a generic approach to 3-D counterparts; in which low heat conductivity of insulator layers makes high dense temperature distribution at layers away from heat sink. In this paper, a thermal-aware methodology for regular 3-D NoCs based on multiple voltage levels is proposed. Given an application task graph, this methodology determines an efficient mapping of tasks onto network tiles, considering inherent... 

End-to-end delay, throughput, energy consumption, and silicon area are the most important design metrics of networks-on-chip (NoCs). Although several analytical models have been previously proposed for predicting such metrics in NoCs, very few of them consider the effect of message waiting time in the buffers of network routers for predicting overall power consumptions and none of them consider structural heterogeneity of network routers. This paper introduces two inter-related analytical models to compute message latency and power consumption of NoCs with arbitrary topology, buffering structure, and routing algorithm. Buffer allocation scheme defines the buffering space for each individual... 

By Technology improvement, tens or hundreds of IP cores, operating complex functions with different frequencies, are mapped on-chip. This results in heterogeneous Multiprocessor System-on-Chip (MPSoC). The most MPSoC design challenges are due to infrastructure interconnect. Network-on-Chip (NoC) with multiple constraints to be satisfied is a promising solution for these challenges. It has been shown that infrastructure topology, routing and switching schemes have great effects on overall interconnect performance under different synthesis and real life traffic patterns. In this paper, we evaluate Butterfly network with arbitrary extra stages as MPSoC infrastructure. Different routing and... 

With technology advances and the emergence of new fabrication and VLSI technologies, current and future chip multiprocessors (CMPs) are expected to have tens to hundreds of processing elements and Gigabytes of on-chip caches, which are connected by a high bandwidth network-on-chip (NoC). Unfortunately, due to limited power budget of a computing system, specially for its processing element(s), it is impossible to keep all cores, caches, and network elements working at highest voltage level—that would resulted in dark silicon computing era, where by employing system-level or architecture-level techniques, one can keep a great portion of a CMP elements OFF (or in dim mode) to meet the power... 

The emergence of new memory technologies provides us with opportunity to enhance the properties of existing memory architectures. One such technology is Phase Change Memory (PCM) which boasts superior scalability, power savings, non-volatility, and a performance competitive to Dynamic Random Access Memory (DRAM). In this paper, we propose a write buffer architecture for Solid-State Drives (SSDs) which attempts to exploit PCM as a DRAM alternative while alleviating its issues such as long write latency, high write energy, and finite endurance. To this end and based on thorough I/O characterization of desktop and enterprise applications, we propose a hybrid DRAM-PCM SSD cache design with an... 

The failure of Dennard scaling has led to the utilization wall that is the source of dark silicon and limits the percentage of a chip that can actively switch within a given power budget. To address this issue, a structure is needed to guarantee the limited power budget along with providing sufficient flexibility and performance for different applications with various communication requirements. In this article, we present a generalpurpose platform for future many-core Chip-Multiprocessors (CMPs) that benefits from the advantages of clustering, Network-on-Chip (NoC) resource sharing among cores, and power gating the unused components of clusters. We also propose two task mapping methods for... 

Although several analytical models have been proposed for wireless sensor networks (WSNs) with different capabilities, very few of them consider the effect of general service distribution as well as design constraints on network performance. This paper presents a new analytical model to compute message latency in a WSN with loop-free Bellman Ford routing strategy. The model considers limited buffer size for each node using M/G/1/k queuing system. Also, contention probability and resource utilization are suitably modeled. The results obtained from simulation experiments confirm that the model exhibits a high degree of accuracy for various network configurations. © 2009 IEEE  

As System-on-Chips (SoCs) grow in complexity and size, proposals of networks-on-chip (NoCs) as the on-chip communication infrastructure are justified by reusability, scalability, and energy efficiency provided by the interconnection networks. Simulation and mathematical analysis offer flexibility for the evaluations under various network configurations. However, the accuracy of such analyzing methods largely depends on the approximations made. On the other hand, prototyping can be used to improve the evaluation accuracy by bringing the design closer to reality. In this paper, we propose a FPGA prototype that is general enough to model different video-processing SoCs where different cores... 

Large Multi-Processor Systems-on-Chip use Networks-on-Chip with a high degree of reusability and scalability for message communication. Therefore, network infrastructure is a crucial element affecting the overall system performance. On the other hand, technology improvements may lead to much energy consumption in micro-routers of an on-chip network. This necessitates an exhaustive analysis of NoCs for future designs. This paper presents a comprehensive analytical model to predict message latency for different data flows traversing across the network. This model considers channel buffers of multiple flits which were not previously studied in NoC context. Also, architectural descriptions of... 

Network-on-Chips are now the popular communication medium to support inter-IP communications in complex on-chip systems with tens to hundreds IP cores. Higher scalability (compared to the traditional shared bus and point-to-point interconnects), throughput, and reliability are among the most important advantages of NoCs. Moreover, NoCs can well match current CAD methodologies mainly relying on modular and reusable structures with regularity of structural pattern. However, since NoCs are resource-limited, determining how to distribute application load over limited on-chip resources (e.g. switches, buffers, virtual channels, and wires) in order to improve the metrics of interest and satisfy...