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Sorting is one of the most fundamental topics in computer science. Since partial sorting with lower costs would be much more feasible than the complete sorting method for some applications, this paper focuses on the architecture sorting N values from M inputs. To meet the real-time processing requirement, hardware acceleration is commonly employed to enhance the performance. However, high-speed computation usually raises power consumption drastically.To overcome that problem, a low-power, high-throughput, and modular hardware design of partial sorting network is presented. By applying a pointer-like design, the comparing modules move the indexes of samples instead of moving the input data directly. Power dissipation is reduced by minimizing switching activities and signal transitions. To prevent unnecessary comparing of the large data set, an iterative architecture is proposed which uses both the low-power sorting module and a novel clipping mechanism. The proposed design was simulated with a 90-nm cell library and the results are compared to those of other works on hardware sorting. Experiment results show that power consumption is reduced by 64.9 percent and high-throughput performance can also be achieved. [ABSTRACT FROM AUTHOR]

This paper introduces a systematic approach to designing high-performance parallel adders based on Counter Tree Diagrams (CTDs). By using CTDs, we can describe addition algorithms at various levels of abstraction. A high-level CTD represents a network of coarse-grained components associated with word-level operands, whereas a low-level CTD represents a network of primitive components that can be directly mapped onto physical devices. The level of abstraction in circuit representation can be changed by decomposition of CTDs. We can derive possible variations of adder structures by decomposing a high-level CTD into low-level CTDs in a formal manner. In this paper, we focus on an application of CTDs to the design of redundant arithmetic adders with limited carry propagation. For any redundant number representation, we can obtain the optimal adder structure by trying every possible CTD decomposition and CTD variable encoding. The potential of the proposed approach is demonstrated through an experimental synthesis of Redundant-Binary (RB) adders with CMOS standard cell libraries. We can successfully obtain RB adders that achieve an about 30-40 percent improvement in terms of power-delay product compared with conventional designs. [ABSTRACT FROM AUTHOR]

As the demand for high-quality Internet increases, emerging network applications are spurring the need for faster, feature-rich, and cost-effective routers. Multifield packet classification in routers has been a computation-intensive data path function for software implementation. Therefore, solutions for packet classification based on hardware design, such as Ternary Content Addressable Memory (TCAM), are necessary to sustain gigabit line processing rate. Traditionally, TCAMs have been designed for storing prefixes. However, multifield packet classification usually involves two fields of arbitrary ranges that are TCP/IP layer 4 source and destination ports. Storing ranges in TCAMs relies on decomposing each individual range into multiple prefixes, which leads to range-to-prefix blowout. To reduce the total number of prefixes needed to represent all ranges, this paper proposes a 2-level TCAM architecture and two range-to-prefix conversion schemes. In the first proposed scheme, designed for disjoint ranges, the maximum number of entries needed in TCAM is 2m - 1 for m disjoint ranges. In the second proposed scheme, designed for contiguous ranges, only m TCAM entries are needed. In a general case of n arbitrary ranges, all ranges can first be converted into disjoint ranges or contiguous ranges and then the proposed algorithms can be applied. As a result, only 4n - 3 TCAM entries are needed for the disjoint ranges and only 2n + 1 TCAM entries are needed for contiguous ranges. This paper also proposes insertion and deletion algorithms to accommodate incremental changes to the range sets. The experiments made show that the proposed range-to-prefix conversion schemes perform better than the existing schemes in terms of the number of required TCAM entries and execution time for range update operations. [ABSTRACT FROM AUTHOR]

Wearable computing has recently gained much popularity as an ambitious vision for future personalized mobile systems. Its aim is intelligent, environment aware systems unobtrusively embedded into the mobile environments of their users. With the combination of complex processing requirements, the necessity of placing sensors and input/output modules at different locations on the user's body, and stringent limits on size, weight, and battery capacity, the design of such systems is an inherently challenging problem. This paper demonstrates how systematic design and quantitative analysis can be applied to wearable architectures. We first present a model that allows various factors influencing the design of a wearable system to be incorporated into formal cost metrics. In particular, we show how to consistently incorporate specific wearable factors such as device placement requirements, ergonomics, and dynamic workload profiles into the model. We then discuss how efficient estimation algorithms can be extended and applied to the evaluation of different architectures with respect to our cost metrics. Finally, we discuss quantitative results from a proof-of-concept case study showing the trade offs between different architectures for a given wearable scenario. Summarized, this paper demonstrates how the description and the design of wearable systems can be put on a systematic, formal basis allowing us to treat them similar as conventional embedded systems. [ABSTRACT FROM AUTHOR]

Scratchpad memories in GPU architectures are employed as software-controlled caches to increase the effective GPU memory bandwidth. Through the use of well-known optimization techniques, such as privatization and tiling, they are properly exploited. Typically, they are banked memories which are addressed with a \textmod(2^N) bank indexing scheme. Although their bandwidth is fully exploited for linear memory accesses, their performance is burdened when non-unit strides appear in memory access patterns because they provoke bank conflicts. This paper explores the use of configurable bit-vector and bitwise XOR-based hash functions to evenly distribute memory addresses of the access patterns over the memory banks, reducing the number of bank conflicts. An exhaustive, but lightweight, search is used to configure bit-vector hash functions. Bitwise hash functions are configured with heuristics. Hardware and software implementations are carried out. For the hardware approach, the experimental results show 24 percent performance speed-up for 22 benchmarks on GPGPU-Sim, a Fermi-like simulator. Bank conflicts are reduced by 96 percent with bit-vector hash functions, and 97 percent with bitwise hash functions using our proposed Minimum Imbalance Heuristic. The software approach, using bit-vector hash functions, demonstrates 23 percent speed-up and 96 percent bank conflict reduction on a Fermi GPU, and 33 percent speed-up and 99 percent bank conflict reduction on a Kepler GPU. [ABSTRACT FROM AUTHOR]

In network on chips (NoCs) design, reconfiguration of NoC is a very effective option for minimizing power consumption, and Gaussian networks can provide significant advantage over the mesh networks in terms of network diameter, average hop distance and so on. In this paper, based on the special topology structure and the static connection rules within Gaussian networks, we present the reconfiguration representation for Gaussian networks and the nature of reconfigurable Gaussian networks. Furthermore, reconfigurable rules of Gaussian networks are proposed to design the constraints for automatic reconfiguration of NoC. [ABSTRACT FROM PUBLISHER]

As a result of huge advancements in VLSI technology, more and more complex circuits are being implemented making not only the whole digital system more prone to faults, but also the fault detector itself susceptible to faults resulting in the requirement of concurrent fault detection architecture of the encoders and decoders. In this paper, we present a multiple-bit parity-based fault detection architecture for parallel CRC computation. After analyzing the parallel implementation of CRC, we present a formulation to generate a multiple-bit parity prediction structure to incorporate the fault detection architecture. Using the formulations of digit level CRC architecture, the checksum is divided into few blocks and predicted multiple-bit parity of the blocks are compared with the actual parity bits. Finally, with the help of software simulation and ASIC implementation, we show that the proposed scheme is highly efficient in terms of fault detection capability whereas it involves small area and time overhead. As an example, we have shown that the worst case area overhead is $25.7$ percent for CRC $-32$ with four parity bits, and corresponding time overhead is $15.6$ percent. [ABSTRACT FROM PUBLISHER]

In this paper we study the problem of characterizing and exploiting the complete flexibility of a special logic architecture, called P-circuits, which realize a Boolean function by projecting it onto overlapping subsets given by a generalized Shannon decomposition. P-circuits are used to restructure logic by pushing some signals towards the outputs. The algorithms proposed so far for exploiting the structural flexibility of P-circuits do not guarantee to find the best implementation, because they cast the problem as the minimization of an incompletely specified function. Instead, here we show that to explore all solutions we must set up the problem as the minimization of a Boolean relation, because there are don’t care conditions that cannot be expressed by single cubes. Finally we report the results obtained using a minimizer of Boolean relations, which improve in a major way with respect to the previous literature. [ABSTRACT FROM PUBLISHER]

Preventing silicon chips from negative, even disastrous thermal hazards has become increasingly challenging these days; Considering thermal effects early in the design cycle is thus required. To achieve this, an accurate yet fast temperature model together with an early-stage, thermally optimized, design flow are needed. In this paper, we present an improved block-based compact thermal model (HotSpot 4.0) that automatically achieves good accuracy even under extreme conditions. The model has been extensively validated with detailed finite-element thermal simulation tools. We also show that properly modeling package components and applying the right boundary conditions are crucial to making full-chip thermal models like HotSpot accurately resemble what happens in the real world. Ignoring or oversimplifying package components can lead to inaccurate temperature estimations and potential thermal hazards that are costly to fix in later design stages. Such a full-chip and package thermal model can then be incorporated into a thermally optimized design flow, where it acts as an efficient communication medium among computer architects, circuit designers, and package designers in early microprocessor design stages to achieve early and accurate design decisions and also faster design convergence. For example, the temperature-leakage interaction can be readily analyzed within such a design flow to predict potential thermal hazards such as thermal runaway. An example SoC design illustrates the importance of adopting such a thermally optimized design flow in early design stages. [ABSTRACT FROM AUTHOR]

In this paper, we present a bit-parallel multiplier for GF(2m) defined by an irreducible pentanomial ixm + xk3 + xk2 + xk1 + 1, where 1 ≤ k1 < k2 < k3 ≤ m/2. In order to design an efficient bit-parallel multiplier, we introduce a shifted polynomial basis and modify a reduction matrix presented by Reyhani-Masoleh and Hasan. As a result, the time complexity of the proposed multiplier is TA + (3 + [log2(m - 1)])Tx, where TA and Tx are the delay of one AND and one XOR gate, respectively. This result matches or outperforms the previously known results. On the other hand, the proposed multiplier has the same space complexity as the previously known multipliers except for special types of irreducible pentanomials. Note that its hardware architecture is similar to that presented by Reyhani-Masoleh and Hasan. [ABSTRACT FROM AUTHOR]

A Taylor Expansion Diagram (TED) is a compact, word-level, canonical representation for data flow computations that can be expressed as multivariate polynomials. TEDs are based on a decomposition scheme using Taylor series expansion that allows one to model word-level signals as algebraic symbols. This power of abstraction, combined with the canonicity and compactness of TED, makes it applicable to equivalence verification of dataflow designs. The paper describes the theory of TEDs and proves their canonicity. It shows how to construct a TED from an HDL design specification and discusses the application of TEDs in proving the equivalence of such designs. Experiments were performed with a variety of designs to observe the potential and limitations of TEDs for dataflow design verification. Application of TEDs to algorithmic and behavioral verification is demonstrated. [ABSTRACT FROM AUTHOR]

This paper presents an enhanced architecture of on-chip pseudorandom test pattern generators, test data decompressors, and test response compactors based on ring generators. The new structure is aimed at improving layout and routing properties while, at the same time, reducing propagation delays introduced by associated phase shifters. [ABSTRACT FROM AUTHOR]

Due to cost, time, and flexibility constraints, computer architects use simulators to explore the design space when developing new processors and to evaluate the performance of potential enhancements. However, despite this dependence on simulators, statistically rigorous simulation methodologies are typically not used in computer architecture research. A formal methodology can provide a sound basis for drawing conclusions gathered from simulation results by adding statistical rigor and, consequently, can increase the architect's confidence in the simulation results. This paper demonstrates the application of a rigorous statistical technique to the setup and analysis phases of the simulation process. Specifically, we apply a Plackett and Burman design to: 1) identify key processor parameters, 2) classify benchmarks based on how they affect the processor, and 3) analyze the effect of processor enhancements. Our results showed that, out of the 41 user-configurable parameters in SimpleScalar, only 10 had a significant effect on the execution time. Of those 10, the number of reorder buffer entries and the L2 cache latency were the two most significant ones, by far. Our results also showed that instruction Precomputation-a value reuse-like microarchitectural technique-primarily improves the processor's performance by relieving integer ALU contention. [ABSTRACT FROM AUTHOR]

Wire delays are a major concern for current and forthcoming processors. One approach to deal with this problem is to divide the processor into semi-independent units referred to as clusters. A cluster usually consists of a local register file and a subset of the functional units, while the L1 data cache typically remains centralized in what we call partially distributed architectures. However, as technology evolves, the relative latency of such a centralized cache will increase, leading to an important impact on performance. In this paper, we propose partitioning the L1 data cache among clusters for clustered VLIW processors. We refer to this kind of design as fully distributed processors. In particular, we propose and evaluate three different configurations: a snoop-based cache coherence scheme, a word-interleaved cache, and flexible L0 buffers managed by the compiler. For each alternative, instruction scheduling techniques targeted to cyclic code are developed. Results for the Mediabench suite show that the performance of such fully distributed architectures is always better than the performance of a partially distributed one with the same amount of resources. In addition, the key aspects of each fully distributed configuration are explored. [ABSTRACT FROM AUTHOR]

Reducing the energy consumption of a real-time system has emerged as an important design concern. In this paper, we propose GAARP, an adaptive scalable architecture targeted toward algorithm-specific tasks for just-in-time performance using the right amount of power. The architecture consists of Globally Asynchronous and Locally Synchronous (GALS) building blocks, where the processing hardware is realized by a set of smaller slices of similar structure, each running synchronously with independent clocks. We demonstrate that, for different real-time commercial applications with algorithm-specific jobs like online transaction processing, digital filtering, Fourier transform, etc., the proposed architecture allows dynamic load-balancing and adaptive intertask voltage scaling based on the load in each of the processing units. Compared to a synchronous implementation of the same functionality, we show that the proposed hardware can achieve higher efficiency in terms of power and performance by exploiting the flexibility to balance the load and change the supply voltage. The architecture also lends itself to process tolerance since it can detect process-shifts for the individual processing units and determine the appropriate operating voltage/frequency for each unit. Simulation results for two representative applications show that, for a modest system configuration and random job distribution, we obtain up to 67 percent improvement in MOPS/W (millions of operations per second per watt) over a fully synchronous implementation. [ABSTRACT FROM AUTHOR]

This tutorial paper examines architectural and circuit design techniques for a microsensor node operating at power levels low enough to enable the use of an energy harvesting source. These requirements place demands on all levels of the design. We propose an architecture for achieving the required ultra-low energy operation and discuss the circuit techniques necessary to implement the system. Dedicated hardware implementations improve the efficiency for specific functionality, and modular partitioning permits fine-grained optimization and power-gating. We describe modeling and operating at the minimum energy point in the subthreshold region for digital circuits. We also examine approaches for improving the energy efficiency of analog components like the transmitter and the ADC. A microsensor node using the techniques we describe can function in an energy-harvesting scenario. [ABSTRACT FROM AUTHOR]

Designing energy-efficient clusters has recently become an important concern to make these systems economically attractive for many applications. Since the cluster interconnect is a major part of the system, the focus of this paper is to characterize and optimize the energy consumption in the entire interconnect. Using a cycle-accurate simulator of an InfiniBand Architecture (IBA) compliant interconnect fabric and actual designs of its components, we investigate the energy behavior on regular and irregular interconnects. The energy profile of the three major components (switches, network interlace cards (NICs), and links) reveals that the links and switch buffers consume the major portion of the power budget. Hence, we focus on energy optimization of these two components. To minimize power in the links, first we investigate the dynamic voltage scaling (DVS) algorithm and then propose a novel dynamic link shutdown (DLS) technique. The DLS technique makes use of an appropriate adaptive routing algorithm to shut down the links intelligently. We also present an optimized buffer design for reducing leakage energy in 70nm technology. Our analysis on different networks reveals that, while DVS is an effective energy conservation technique, it incurs significant performance penalty at low to medium workload. Moreover, energy saving with DVS reduces as the buffer leakage current becomes significant with 70nm design. On the other hand, the proposed DLS technique can provide optimized performance-energy behavior (up to 40 percent energy savings with less than 5 percent performance degradation in the best case) for the cluster interconnects. [ABSTRACT FROM AUTHOR]

Energy conservation without performance degradation is an important goal for battery-operated computers, such as laptops and hand-held assistants. In this paper, we study application-supported device management for optimizing energy and performance. In particular, we consider application transformations that increase device idle times and inform the operating system about the length of each upcoming period of idleness. We use modeling and experimentation to assess the potential energy and performance benefits of this type of application support for a laptop disk. Furthermore, we propose and evaluate a compiler framework for performing the transformations automatically. Our main modeling results show that the transformations are potentially beneficial. However, our experimental results with six real laptop applications demonstrate that, unless applications are transformed, they cannot accrue any of the predicted benefits. In addition, they show that our compiler can produce almost the same performance and energy results as hand-modifying applications. Overall, we find that the transformations can reduce disk energy consumption from 55 percent to 89 percent with a degradation in performance of at most 8 percent. [ABSTRACT FROM AUTHOR]

Two architectures for modulo 2^n+1 adders are introduced in this paper. The first one is built around a sparse carry computation unit that computes only some of the carries of the modulo 2^n+1 addition. This sparse approach is enabled by the introduction of the inverted circular idempotency property of the parallel-prefix carry operator and its regularity and area efficiency are further enhanced by the introduction of a new prefix operator. The resulting diminished-1 adders can be implemented in smaller area and consume less power compared to all earlier proposals, while maintaining a high operation speed. The second architecture unifies the design of modulo 2^n\pm 1 adders. It is shown that modulo 2^n+1 adders can be easily derived by straightforward modifications of modulo 2^n-1 adders with minor hardware overhead. [ABSTRACT FROM PUBLISHER]