Hardware Support for Prescient Instruction Prefetch
This paper proposes and evaluates hardware mechanisms for supporting prescient instruction prefetch — an approach to improving single-threaded application performance by using helper threads to perform instruction prefetch. We demonstrate the need for enabling store-to-load communication and selective instruction execution when directly pre-executing future regions of an application that suffer I-cache misses. Two novel hardware mechanisms, safe-store and YAT-bits, are introduced that help satisfy these requirements. This paper also proposes and evaluates .nite state machine recall, a technique for limiting pre-execution to branches that are hard to predict by leveraging a counted I-prefetch mechanism. On a research Itanium®SMT processor with next line and streaming I-prefetch mechanisms that incurs latencies representative of next generation processors, prescient instruction prefetch can improve performance by an average of 10.0% to 22% on a set of SPEC 2000 benchmarks that suffer significant I-cache misses. Prescient instruction prefetch is found to be competitive against even the most aggressive research hardware instruction prefetch technique: fetch directed instruction prefetch.

title: Intel nehalem processor core made FPGA synthesizable
abstract: We present a FPGA-synthesizable version of the Intel Nehalem processor core, synthesized, partitioned and mapped to a multi-FPGA emulation system consisting of Xilinx Virtex-4 and Virtex-5 FPGAs. To our knowledge, this is the first time a modern state-of-the-art x86 design with the out-of-order micro-architecture is made FPGA synthesizable and capable of high-speed cycle-accurate emulation. Unlike the Intel Atom core which was made FPGA synthesizable on a single Xilinx Virtex-5 in a previous endeavor, the Nehalem core is a more complex design with aggressive clock-gating, double phase latch RAMs, and RTL constructs that have no true equivalent in FPGA architectures. Despite these challenges, we are successful in making the RTL synthesizable with only 5% RTL code modifications, partitioning the design across five FPGAs, and emulating the core at 520 KHz. The synthesizable Nehalem core is able to boot Linux and execute standard x86 workloads with all architectural features enabled.

title: On Fault-Tolerant Computation of Orthogonal Transforms on Hypercube Computers

title: Helper threads via virtual multithreading
abstract: Memory latency dominates the performance of many applications on modern processors, despite advances in caches and prefetching techniques. Numerous prefetching techniques, both in hardware and software, try to alleviate the memory bottleneck. One such technique, known as helper threading improves single-thread performance on a simultaneous multithreaded architecture (SMT), which shares processor resources, including caches, among logical threads. It uses otherwise idle hardware thread contexts to execute speculative threads on behalf of the main thread. Helper threading accelerates a program by exploiting a processor's multithreading capability to run assist threads. Based on the helper threading usage model, virtual multithreading (VMT), a form of switch-on-event user-level multithreading, can improve performance for real-world workloads with a wall-clock speedup of 5.0 to 38.5 percent

title: Quantitative evaluation of the register stack engine and optimizations for future Itanium processors
abstract: This paper examines the efficiency of the register stack engine (RSE) in the canonical Itanium architecture, and introduces novel optimization techniques to enhance the RSE performance. To minimize spills and fills of the physical register file, optimizations are applied to reduce internal fragmentation in statically allocated register stack frames. Through the use of dynamic register usage (DRU) and dead register value information (DVI), the processor can dynamically guide allocation and deallocation of register frames. Consequently, a speculatively allocated register frame with a dynamically determined frame size can be much smaller than the statically determined frame size, thus achieving minimum spills and fills. Using the register stack engine (RSE) in the canonical Itanium architecture as the baseline reference, we thoroughly study and gauge the tradeoffs of the RSE and the proposed optimizations using a set of SPEC CPU2000 benchmarks built with different compiler optimizations. A combination of frame allocation policies using the most frequent frame size and deallocation policies using dead register information proves to be highly effective. On average, a 71% reduction in aggregate spills and fills can be achieved over the baseline reference.

title: Pangaea: A tightly-coupled IA32 heterogeneous chip multiprocessor
abstract: Moore's Law and the drive towards performance efficiency have led to the on-chip integration of general-purpose cores with special-purpose accelerators. Pangaea is a heterogeneous CMP design for non-rendering workloads that integrates IA32 CPU cores with non-IA32 GPU-class multi-cores, extending the current state-of-the-art CPU-GPU integration that physically “fuses” existing CPU and GPU designs. Pangaea introduces (1) a resource repartitioning of the GPU, where the hardware budget dedicated for 3D-specific graphics processing is used to build more general-purpose GPU cores, and (2) a 3-instruction extension to the IA32 ISA that supports tighter architectural integration and fine-grain shared memory collaborative multithreading between the IA32 CPU cores and the non-IA32 GPU cores. We implement Pangaea and the current CPU-GPU designs in fully-functional synthesizable RTL based on the production quality RTL of an IA32 CPU and an Intel GMA X4500 GPU. On a 65 nm ASIC process technology, the legacy graphics-specific fixed-function hardware has the area of 9 GPU cores and total power consumption of 5 GPU cores. With the ISA extensions, the latency from the time an IA32 core spawns a GPU thread to the time the thread begins execution is reduced from thousands of cycles to fewer than 30 cycles. Pangaea is synthesized on a FPGA-based prototype and runs off-the-shelf IA32 OSes. A set of general-purpose non-graphics workloads demonstrate speedups of up to 8.8×.

title: A Fast and Robust Ellipse Detection Algorithm Based on Pseudo-random Sample Consensus
abstract: Ellipse is one of the most common features that appears in images. Over years in research, real-timing and robustness have been two very challenging problems aspects of ellipse detection. Aiming to tackle them both, we propose an ellipse detection algorithm based on pseudo-random sample consensus (PRANSAC). In PRANSAC we improve a contour-based ellipse detection algorithm (CBED), which was presented in our previous work. In addition, the parallel thinning algorithm is employed to eliminate useless feature points, which increases the time efficiency of our detection algorithm. In order to further speed up, a 3-point ellipse fitting method is introduced. In terms of robustness, a "robust candidate sequence" is proposed to improve the robustness performance of our detection algorithm. Compared with the state-of-the-art ellipse detection algorithms, experimental results based on real application images show that significant improvements in time efficiency and performance robustness of the proposed algorithm have been achieved.

title: Implementing a scalable ASC processor
abstract: Previous papers (Walker et al. (2001); Wu et al. (2002)) have described our implementation of a small prototype processor and control unit for associative computing, called the ASC processor. That initial prototype was implemented on an Altera education board using an Altera FLEX 10K FPGA, and was limited to an unrealistic 4 processing elements (PE). This paper describes a more complete implementation - a scalable ASC processor that can scale up to 52 PE on an Altera APEX 20KE board, or further on larger FPGA. This paper also proposes extensions to support multiple control units and control parallelism.

title: A dependable Peer-to-Peer computing platform
abstract: This paper discusses a dependable and widely applicable Peer-to-Peer (P2P) computing platform. As the existing P2P computing platforms are limited due to the lack of support for various computational models, this paper proposes a workflow management mechanism to support task dependency in parallel programs while increasing computing efficiency. In general, task dependency leads to a serious performance degradation for failed task re-execution because of volatile peers. Therefore, it results in low dependability. Here, dependability is defined as a comparison of the actual performance with task failures to the theoretical one without failure on a P2P computing platform. Redundant task dispatch and a runtime optimization method are proposed to guarantee high dependability even with highly volatile peers. Large-scale simulation results indicate that the computing platform efficiently solves the problem of P2P computing due to volatile peers.

title: A Performance Study of Secure Data Mining on the Cell Processor
abstract: This paper examines the potential of the Cell processor as a platform for secure data mining on the future volunteer computing systems. Volunteer computing platforms have the potential to provide massive computing power. However, privacy and security concerns prevent using volunteer computing for data mining of sensitive data. The Cell processor comes with a hardware security feature. The secure volunteer data mining can be achieved by using this hardware security feature. In this paper, we present a general security scheme for the volunteer computing, and a secure parallelized K-Means clustering algorithm for the Cell processor. We also evaluate the performance of the algorithm on the Cell secure system simulator. Evaluation results indicate that the proposed secure data clustering outperforms a non-secure clustering algorithm on the general purpose CPU, but incurs a huge performance overhead introduced by the decryption process of the Cell security features.

title: Adaptive Tracking Control for the Output PDFs Based on Dynamic Neural Networks
abstract: In this paper, a novel adaptive tracking control strategy is established for general non-Gaussian stochastic systems based on two-step neural network models. The objective is to control the conditional PDF of the system output to follow a given target function by using dynamic neural network models. B-spline neural networks are used to model the dynamic output probability density functions (PDFs), then the concerned problem is transferred into the tracking of given weights corresponding to the desired PDF. The dynamic neural networks with undetermined parameters are employed to identify the nonlinear relationships between the control input and the weights. To achieve control objective, an adaptive state feedback controller is given to estimate the unknown parameters and control the nonlinear dynamics.