International Technology Roadmap for Semiconductors 2003の要求清浄度について － シリコンウエハ表面と雰囲気環境に要求される清浄度, 分析方法の現状について －

Fast Fourier Transform

Memory isolation is a key property of a reliable and secure computing system--an access to one memory address should not have unintended side effects on data stored in other addresses. However, as DRAM process technology scales down to smaller dimensions, it becomes more difficult to prevent DRAM cells from electrically interacting with each other. In this paper, we expose the vulnerability of commodity DRAM chips to disturbance errors. By reading from the same address in DRAM, we show that it is possible to corrupt data in nearby addresses. More specifically, activating the same row in DRAM corrupts data in nearby rows. We demonstrate this phenomenon on Intel and AMD systems using a malicious program that generates many DRAM accesses. We induce errors in most DRAM modules (110 out of 129) from three major DRAM manufacturers. From this we conclude that many deployed systems are likely to be at risk. We identify the root cause of disturbance errors as the repeated toggling of a DRAM row's wordline, which stresses inter-cell coupling effects that accelerate charge leakage from nearby rows. We provide an extensive characterization study of disturbance errors and their behavior using an FPGA-based testing platform. Among our key findings, we show that (i) it takes as few as 139K accesses to induce an error and (ii) up to one in every 1.7K cells is susceptible to errors. After examining various potential ways of addressing the problem, we propose a low-overhead solution to prevent the errors

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Flipping bits in memory without accessing them: an experimental study of DRAM disturbance errors

The main characteristic of Reconfigurable Computing is the presence of hardware that can be reconfigured to implement specific functionality more suitable for specially tailored hardware than on a simple uniprocessor. Reconfigurable computing systems join microprocessors and programmable hardware in order to take advantage of the combined strengths of hardware and software and have been used in applications ranging from embedded systems to high performance computing. Many of the fundamental theories have been identified and used by the Hardware/Software Co-Design research field. Although the same background ideas are shared in both areas, they have different goals and use different approaches.This book is intended as an introduction to the entire range of issues important to reconfigurable computing, using FPGAs as the context, or "computing vehicles" to implement this powerful technology. It will take a reader with a background in the basics of digital design and software programming and provide them with the knowledge needed to be an effective designer or researcher in this rapidly evolving field.

· Treatment of FPGAs as computing vehicles rather than glue-logic or ASIC substitutes
· Views of FPGA programming beyond Verilog/VHDL
· Broad set of case studies demonstrating how to use FPGAs in novel and efficient ways

Reconfigurable Computing: The Theory and Practice of FPGA-Based Computation

In this paper, we present a polymorphic processor paradigm incorporating both general-purpose and custom computing processing. The proposal incorporates an arbitrary number of programmable units, exposes the hardware to the programmers/designers, and allows them to modify and extend the processor functionality at will. To achieve the previously stated attributes, we present a new programming paradigm, a new instruction set architecture, a microcode-based microarchitecture, and a compiler methodology. The programming paradigm, in contrast with the conventional programming paradigms, allows general-purpose conventional code and hardware descriptions to coexist in a program: In our proposal, for a given instruction set architecture, a onetime instruction set extension of eight instructions, is sufficient to implement the reconfigurable functionality of the processor. We propose a microarchitecture based on reconfigurable hardware emulation to allow high-speed reconfiguration and execution. To prove the viability of the proposal, we experimented with the MPEG-2 encoder and decoder and a Xilinx Virtex II Pro FPGA. We have implemented three operations, SAD, DCT, and IDCT. The overall attainable application speedup for the MPEG-2 encoder and decoder is between 2.64-3.18 and between 1.56-1.94, respectively, representing between 93 percent and 98 percent of the theoretically obtainable speedups.

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The MOLEN polymorphic processor

We introduce a 64-bit ANSI/IEEE Std 754-1985 floating point design of a hardware matrix multiplier optimized for FPGA implementations. A general block matrix multiplication algorithm, applicable for an arbitrary matrix size is proposed. The algorithm potentially enables optimum performance by exploiting the data locality and reusability incurred by the general matrix multiplication scheme and considering the limitations of the I/O bandwidth and the local storage volume. We implement a scalable linear array of processing elements (PE) supporting the proposed algorithm in the Xilinx Virtex II Pro technology. Synthesis results confirm a superior performance-area ratio compared to related recent works. Assuming the same FPGA chip, the same amount of local memory, and the same I/O bandwidth, our design outperforms related proposals by at least 1.7X and up to 18X consuming the least reconfigurable resources. A total of 39 PEs can be integrated into the xc2vp125-7 FPGA, reaching performance of, e.g., 15.6 GFLOPS with 1600 KB local memory and 400 MB/s external memory bandwidth.

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64-bit floating-point FPGA matrix multiplication

Many march tests have already been designed to cover faults of different fault models. The complexity of these tests arises when linked faults are taken into consideration. This paper gives an overview of the most important and commonly used fault models, including the industry's popular disturb fault model. The fault coverage of march tests is analysed in a novel way, i.e., in terms of their detection capabilities for: simple faults, and linked faults; whereby the infinite class of linked faults has been reduced to a set of realistic linked faults. Thereafter the paper presents a methodology to design tests for realistic linked faults, resulting in the new tests March LR, March LRD and March LRDD. These new tests will be shown to be more efficient and to offer a higher fault coverage than comparable existing tests.

March LR: a test for realistic linked faults

Reconfigurable computational architectures are envisioned to deliver power efficient, high performance, flexible platforms for embedded systems design. The coarse-grained reconfigurable architecture ADRES (Architecture for Dynamically Reconfigurable Embedded Systems) and its compiler offer a tool flow to design sparsely interconnected 2D array processors with an arbitrary number of functional units, register files and interconnection topologies. This article presents an architectural exploration methodology and its results for the first implementation of the ADRES architecture on a 90nm standard-cell technology. We analyze performance, energy and power trade-offs for two typical kernels from the multimedia and wireless domains: IDCT and FFT. Architecture instances of different sizes and interconnect structures are evaluated with respect to their power versus performance trade-offs. An optimized architecture is derived. A detailed power breakdown for the individual components of the selected architecture is presented.

Architectural exploration of the ADRES coarse-grained reconfigurable array

In this paper, we present the DWARV C-to-VHDL generation toolset. The toolset provides support for broad range of application domains. It exploits the operation parallelism, available in the algorithms. Our designs are generated with a view of actual hardware/software co-execution on a real hardware platform. The carried experiments on the MOLEN polymorphic processor prototype suggest overall application speedups between 1.4x and 6.8x, corresponding to 13% to 94% of the theoretically achievable maximums, constituted by Amdahl's law.

Georgi Gaydadjiev

Papers

The MOLEN polymorphic processor

64-bit floating-point FPGA matrix multiplication

March LR: a test for realistic linked faults

Architectural exploration of the ADRES coarse-grained reconfigurable array

DWARV: Delftworkbench Automated Reconfigurable VHDL Generator