Customized accelerators have revolutionized modern computing by delivering substantial gains in energy efficiency and performance through hardware specialization. Field-Programmable Gate Arrays (FPGAs) play a crucial role in this paradigm, offering unparalleled flexibility and high-performance potential. High-Level Synthesis (HLS) and source-to-source compilers have simplified FPGA development by translating high-level programming languages into hardware descriptions enriched with directives. However, achieving high Quality of Results (QoR) remains a significant challenge, requiring intricate code transformations, strategic directive placement, and optimized data communication. This article presents Prometheus , a holistic optimization framework that integrates key optimizations - including task fusion, tiling, loop permutation, computation-communication overlap, and concurrent task execution -into a unified design space. By leveraging Non-Linear Programming (NLP) methodologies , Prometheus explores the optimization space under strict resource constraints, enabling automatic bitstream generation. Unlike existing frameworks, Prometheus considers interdependent transformations and dynamically balances computation and memory access. We evaluate Prometheus across multiple benchmarks, demonstrating its ability to maximize parallelism, minimize execution stalls, and optimize data movement. The results showcase its superior performance compared to state-of-the-art FPGA optimization frameworks, highlighting its effectiveness in delivering high QoR while reducing manual tuning efforts.

Boolean satisfiability (SAT) solving is the first known NP-complete problem and is widely used in many application domains. Over the years, there have been so many consistent improvements in this area such that larger instances can be solved relatively quickly. Although these improvements have found their way onto CPU implementations, there has been limited progress adopting this on hardware accelerators mainly because it is difficult to implement the dynamic data structures needed to support a modern SAT solving algorithm.

The increasing complexity of large-scale FPGA accelerators poses significant challenges in achieving high performance while maintaining design productivity. High-level synthesis (HLS) has been adopted as a solution, but the mismatch between the high-level description and the physical layout often leads to suboptimal operating frequency. Although existing proposals for high-level physical synthesis, which use coarse-grained design partitioning, floorplanning, and pipelining to improve frequency, have gained traction, they lack a framework enabling (1) pipelining of real-world designs at arbitrary hierarchical levels, (2) integration of HLS blocks, vendor IPs, and handcrafted RTL designs, (3) portability to emerging new target FPGA devices, and (4) extensibility for the easy implementation of new design optimization tools.

Streaming applications compose an important portion of the workloads that FPGAs may accelerate but suffer from inefficient data movement. The inefficiency stems from copying data indirectly into the FPGA DRAM rather than directly into its on-chip memory, substantially diminishing the end-to-end speedup, especially for small workloads (hundreds of kilobytes). AMD Xilinx's Host Memory IP (HMI) aims to address the data movement problem by exposing to the developer an High-Level Synthesis (HLS) interface that moves the data from the host directly to the FPGA's on-chip memory. However, using HMI purely for its interface without additional code changes incurred a 3.3x slowdown in comparison with the current programming model. The slowdown mainly originates from OpenCL call overhead and the kernel control logic unnecessarily switching states. To overcome these issues, we propose Host Memory Library (HMLib), an efficient HLS-based library that facilitates data transfer on behalf of the user. HMLib not only optimizes the runtime stack for efficient data transfer, but also provides HLS compatible and user-friendly interfaces. We demonstrate HMLib's effectiveness for streaming applications (Deflate compression and CRC32) with improvements of up to up to 36.2X over OpenCL-DDR and up to 79.5X over raw HMI for small-scale data while maintaining little-to-no performance loss for large scale inputs. We plan to open source our work in the future.

Genome sequencing is one of the key applications in healthcare and has a great potential to realize precision medicine and personalized healthcare. However, its computing process is very time consuming. Even pre-processing the raw sequence data of a whole genome for a single person to the analysis ready data can take several days on a single-core CPU.In this paper, we propose to accelerate the performance of the widely used Genome Analysis ToolKit (GATK) using FPGAs. More specifically, we focus on the algorithm and hardware co-design for the Base Quality Score Re-calibration (BQSR) step in GATK, which is an important and time-consuming step to correct systematic errors made by a sequencing machine. Prior studies did not consider hardware acceleration for BQSR because it requires a large amount of memory with random access and has a lot of control flow. To address these challenges, we first adapt the algorithm to resolve the random memory access conflicts to achieve a fully pipelined accelerator design and reduce its dataset size. Second, we leverage the newly introduced large-capacity UltraRAM (URAM) in Xilinx UltraScale+ FPGAs to butter BQSR’s large dataset on chip, and further optimize its operating frequency. Finally, we also explore the coarse-grained pipeline and parallelism to improve the overall performance of the BQSR accelerator. Compared to the latest software implementation of BQSR on GATK 4.1, running on single-thread and 56-thread CPUs (14nm Xeon E5-2680 v4), our FPGA accelerator running on Xilinx 16nmUltraScale+VCUl525 board achieves up to 40. 7x and 8. 5x speedups, respectively.

This paper aims to better understand the performance differences between FPGAs and GPUs. We intentionally begin with a widely used GPU-friendly benchmark suite, Rodinia, and port 15 of the kernels onto FPGAs using HLS C. Then we propose an analytical model to compare their performance. We find that for 6 out of the 15 ported kernels, today's FPGAs can provide comparable performance or even achieve better performance than the GPU, while consuming an average of 28% of the GPU power. Besides lower clock frequency, FPGAs usually achieve a higher number of operations per cycle in each customized deep pipeline, but lower effective parallel factor due to the far lower off-chip memory bandwidth. With 4x more memory bandwidth, 8 out of the 15 FPGA kernels are projected to achieve at least half of the GPU kernel performance.

Data compression techniques have been widely used to reduce data storage and movement overhead, especially in the big data era. While FPGAs are well suited to accelerate the computation-intensive lossless compression algorithms, big data compression with parallel requests intrinsically poses two challenges to the overall system throughput. First, scaling existing single-engine FPGA compression accelerator designs already encounters bottlenecks which will result in lower clock frequency, saturated throughput and lower area efficiency. Second, when such FPGA compression accelerators are integrated with the processors, the overall system throughput is typically limited by the communication between a CPU and an FPGA. We propose a novel multi-way parallel and fully pipelined architecture to achieve high-throughput lossless compression on modern Intel-Altera HARPv2 platforms. To compensate for the compression ratio loss in a multi-way design, we implement novel techniques, such as a better data feeding method and a hash chain to increase the hash dictionary history. Our accelerator kernel itself can achieve a compression throughput of 12.8 GB/s (2.3x better than the current record throughput) and a comparable compression ratio of 2.03 for standard benchmark data. Our approach enables design scalability without a reduction in clock frequency and also improves the performance per area efficiency (up to 1.5x). Moreover, we exploit the high CPU-FPGA communication bandwidth of HARPv2 platforms to improve the compression throughput of the overall system, which can achieve an average practical end-to-end throughput of 10.0 GB/s (up to 12 GB/s for larger input files) on HARPv2.

The notorious power wall has significantly limited the scaling for general-purpose processors. To address this issue, various accelerators, such as GPUs and FPGAs, emerged to achieve better performance and energy-efficiency. Between these two programmable accelerators, a natural question arises: which applications are better suited for FPGAs, which for GPUs, and why?

Data compression techniques have been widely used to reduce the data storage and movement overhead, especially in the big data era. Recent studies demonstrate the great promise of FPGAs to improve the throughput of lossless compression algorithms that are very computation-intensive. However, when such FPGA-based compression accelerators are integrated with the processors, the overall system throughput is typically limited by the communication between a CPU and an FPGA. This study proposes a novel scheme to achieve high-throughput lossless compression on modern Intel-Altera HARPv2 platforms, where a Xeon CPU and an Altera FPGA are tightly coupled to improve the CPU-FPGA communication. First, it implements a multi-way parallel and fully pipelined compression accelerator based on Deflate algorithm. The accelerator itself can achieve a maximum throughput of 12.8 GB/s and a compression ratio of 2.03 over standard benchmarks. In addition, various trade-offs among compression throughput, compression ratio, FPGA resource utilization and scalability are explored to optimize the accelerator design based on different application requirements. Moreover, this study exploits the high CPU-FPGA communication bandwidth of HARPv2 platforms to improve the compression throughput of the overall system, which can achieve an average practical end-to-end throughput of 10.0 GB/s (up to 12 GB/s for larger input files) on HARPv2.

Unlike outbound traffic, incoming traffic distribution to a multi-homed AS is influenced mainly by the upstream ISPs' routing policies. Currently, only a handful of mechanisms is available for such an AS to engineer the traffic volume coming into these links. We concentrate on the problem of re-distributing the incoming traffic across the multiple links. We consider the approach of AS path prepending which artificially inflates the length of the AS path to the network reported in BGP (border gateway protocol) messages, with the hope of diverting some of the traffic from one incoming link to another. Although this approach has already been deployed by many ASes, it is often performed on a trial-and-error basis; there is also a lack of a detailed measurement study on the effectiveness of this approach. The paper attempts to fill these gaps. In particular, we have proposed a complete procedure based on the AS path prepending method to engineer incoming traffic according to some traffic control policy. The procedure includes passive measurements, active measurements, and traffic change prediction. We have deployed this approach to a noncommercial site and evaluated its effectiveness based on measurements collected over six months. Similar measurement cycles can be replicated in other multi-homed ASes by deploying the procedure and the associated software tools.