Browsing by Author "Helal, Ahmed E."

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    Accelerating Workloads on FPGAs via OpenCL: A Case Study with OpenDwarfs
    Verma, Anshuman; Helal, Ahmed E.; Krommydas, Konstantinos; Feng, Wu-chun (Department of Computer Science, Virginia Polytechnic Institute & State University, 2016-05-13)
    For decades, the streaming architecture of FPGAs has delivered accelerated performance across many application domains, such as option pricing solvers in finance, computational fluid dynamics in oil and gas, and packet processing in network routers and firewalls. However, this performance comes at the expense of programmability. FPGA developers use hardware design languages (HDLs) to implement the application data and control path and to design hardware modules for computational pipelines, memory management, synchronization, and communication. This process requires extensive knowledge of logic design, design automation tools, and low-level details of FPGA architecture, this consumes significant development time and effort. To address this lack of programmability of FPGAs, OpenCL provides an easy-to-use and portable programming model for CPUs, GPUs, APUs, and now, FPGAs. Although this significantly improved programmability yet an optimized GPU implementation of kernel may lack performance portability for FPGA. To improve the performance of OpenCL kernels on FPGAs we identify general techniques to optimize OpenCL kernels for FPGAs under device-specific hardware constraints. We then apply these optimizations techniques to the OpenDwarfs benchmark suite, which has diverse parallelism profiles and memory access patterns, in order to evaluate the effectiveness of the optimizations in terms of performance and resource utilization. Finally, we present the performance of structured grids and N-body dwarf-based benchmarks in the context of various optimization along with their potential re-factoring. We find that careful design of kernels for FPGA can result in a highly efficient pipeline achieving 91% of theoretical throughput for the structured grids dwarf. Index Terms—OpenDwarfs; FPGA; OpenCL; GPU; MIC; Accelerators; Performance Portability
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    AutoMatch: Automated Matching of Compute Kernels to Heterogeneous HPC Architectures
    Helal, Ahmed E.; Feng, Wu-chun; Jung, Changhee; Hanafy, Yasser Y. (Department of Computer Science, Virginia Polytechnic Institute & State University, 2016-12-13)
    HPC systems contain a wide variety of heterogeneous computing resources, ranging from general-purpose CPUs to specialized accelerators. Porting sequential applications to such systems for achieving high performance requires significant software and hardware expertise as well as extensive manual analysis of both the target architectures and applications to decide the best performing architecture and implementation technique for each application. To streamline this tedious process, this paper presents AutoMatch, a tool for automated matching of compute kernels to heterogeneous HPC architectures. AutoMatch analyzes the sequential application code and automatically predicts the performance of the best parallel implementation of its compute kernels on different hardware architectures. AutoMatch leverages such prediction results to identify the best device for each kernel from a set of devices including multi-core CPUs and many-core GPUs. In addition, it estimates the relative execution cost between the different architectures to drive a workload distribution scheme, which enables end users to efficiently exploit the available compute resources across multiple heterogeneous architectures. We demonstrate the efficacy of AutoMatch, using a set of open-source HPC applications and benchmarks with different parallelism profiles and memory-access patterns. The empirical evaluation shows that AutoMatch is highly accurate across five different heterogeneous architectures, identifying the best architecture for each workload in 96% of the test cases, and its workload distribution scheme has a comparable performance to a profiling-driven oracle.
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    Bridging the Performance-Programmability Gap for FPGAs via OpenCL: A Case Study with OpenDwarfs
    Krommydas, Konstantinos; Helal, Ahmed E.; Verma, Anshuman; Feng, Wu-chun (Department of Computer Science, Virginia Polytechnic Institute & State University, 2016-05-13)
    For decades, the streaming architecture of FPGAs has delivered accelerated performance across many application domains, such as option pricing solvers in finance, computational fluid dynamics in oil and gas, and packet processing in network routers and firewalls. However, this performance has come at the significant expense of programmability, i.e., the performance-programmability gap. In particular, FPGA developers use hardware design languages (HDLs) to implement the application data path and to design hardware modules for computation pipelines, memory management, synchronization, and communication. This process requires extensive low-level knowledge of the target FPGA architecture and consumes significant development time and effort. To address this lack of programmability of FPGAs, OpenCL provides an easy-to-use and portable programming model for CPUs, GPUs, APUs, and now, FPGAs. However, this significantly improved programmability can come at the expense of performance; that is, there still remains a performance-programmability gap. To improve the performance of OpenCL kernels on FPGAs, and thus, bridge the performance-programmability gap, we identify general techniques to optimize OpenCL kernels for FPGAs under device-specific hardware constraints. We then apply these optimization techniques to the OpenDwarfs benchmark suite, with its diverse parallelism profiles and memory access patterns, in order to evaluate the effectiveness of the optimizations in terms of performance and resource utilization. Finally, we present the performance of the optimized OpenDwarfs, along with their potential re-factoring, to bridge the performance gap from programming in OpenCL versus programming in a HDL. Index Terms—OpenDwarfs; FPGA; OpenCL; GPU; GPGPU; MIC; Accelerators; Performance Portability
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    CommAnalyzer: Automated Estimation of Communication Cost on HPC Clusters Using Sequential Code
    Helal, Ahmed E.; Jung, Changhee; Feng, Wu-chun; Hanafy, Yasser Y. (Department of Computer Science, Virginia Polytechnic Institute & State University, 2017-08-14)
    MPI+X is the de facto standard for programming applications on HPC clusters. The performance and scalability on such systems is limited by the communication cost on different number of processes and compute nodes. Therefore, the current communication analysis tools play a critical role in the design and development of HPC applications. However, these tools require the availability of the MPI implementation, which might not exist in the early stage of the development process due to the parallel programming effort and time. This paper presents CommAnalyzer, an automated tool for communication model generation from a sequential code. CommAnalyzer uses novel compiler analysis techniques and graph algorithms to capture the inherent communication characteristics of sequential applications, and to estimate their communication cost on HPC systems. The experiments with real-world, regular and irregular scientific applications demonstrate the utility of CommAnalyzer in estimating the communication cost on HPC clusters with more than 95% accuracy on average.
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    A Composable Workflow for Productive FPGA Computing via Whole-Program Analysis and Transformation (with Code Excerpts)
    Sathre, Paul; Helal, Ahmed E.; Feng, Wu-chun (Department of Computer Science, Virginia Polytechnic Institute & State University, 2018-07-24)
    We present a composable workflow to enable highly-productive heterogeneous computing on FPGAs. The workflow consists of a trio of static analysis and transformation tools: (1) a whole-program, source-to-source translator to transform existing parallel code to OpenCL, (2) a set of OpenCL kernel linters, which target FPGAs to detect possible semantic errors and performance traps, and (3) a whole-program OpenCL linter to validate the host-to-device interface of OpenCL programs. The workflow promotes rapid realization of heterogeneous parallel code across a multitude of heterogeneous computing environments, particularly FPGAs, by providing complementary tools for automatic CUDA-to-OpenCL translation and compile-time OpenCL validation in advance of very expensive compilation, placement, and routing on FPGAs. The proposed tools perform whole-program analysis and transformation to tackle realworld, large-scale parallel applications. The efficacy of the workflow tools is demonstrated via a representative translation and analysis of a sizable CUDA finite automata processing engine as well as the analysis and validation of an additional 96 OpenCL benchmarks.