arXiv subjects

Andrew Boutros

Publications and source records attributed to Andrew Boutros.

11 recordsLinked to original sources

arXiv2026

From Patterns to Parsers: Automatic Generation of Efficient Hardware Parsers for FPGAs

This work presents an open-source tool for automatically generating efficient hardware parsers from high-level specifications. It uses a parsing intermediate representation (PIR) that decouples application-specific frontends from a common register-transfer level (RTL) generation backend. The backend produces optimized, human-readable SystemVerilog, handling FSM generation, byte-alignment, and multi-cycle field straddling for arbitrary datapath widths. The tool also extends pattern matching beyond simple equality checks by introducing custom symbolic tokens to support operations that existing parser generators cannot express, such as range validation, negation, and comparisons against external ports. We demonstrate two end-to-end flows using a P4 frontend for Ethernet protocol parsing and a Snort frontend for network intrusion detection, both using the same unmodified backend. The generated Ethernet parsers achieve up to 226% higher operating frequency and up to 97% fewer FPGA logic resources than prior work. A controlled synthetic study further shows that the tool's hierarchical pattern decomposition yields up to 8x resource utilization reduction over monolithic designs. Our open-source framework enables designers to rapidly implement high-performance, resource-efficient, vendor-agnostic hardware parsers for diverse applications.

cs.AR↗

arXiv2026

Jack of All Scales: A Versatile FPGA Tensor Block for MXFP Precisions

Modern deep learning workloads increasingly rely on narrow numerical formats to improve efficiency and reduce memory footprint. The recently standardized microscaling floating-point (MXFP) family of formats, including MXFP8, MXFP6, and MXFP4, offers a practical approach to low-precision inference, yet the digital signal processing (DSP) blocks in current FPGA architectures offer limited native support for these formats. In this work, we first present a comprehensive characterization of MXFP dot product implementations on Altera Agilex-5 FPGAs, exploring a range of strategies spanning pure soft logic, DSP blocks in fixed-point, floating-point, and tensor modes. Our results show that while the tensor mode delivers the highest arithmetic density for MXFP4 (E2M1) and MXFP6 (E2M3), it cannot implement MXFP6 (E3M2) or any MXFP8 precisions, forcing designers to fall back to lower-density alternatives. Motivated by this gap, we propose targeted modifications to the DSP block's internal tensor-mode architecture that enable native support for all MXFP precisions while retaining backward compatibility. We estimate the area cost of these modifications using a simplified version of the Agilex-5 DSP block core implemented using the open-source ASAP7 PDK. We evaluate a variety of modified DSP block designs that present a tradeoff between format coverage, arithmetic density, and area overhead. Our preferred design point increases the DSP tile area by 36%, corresponding to only 1.8\% of the total FPGA die area. We evaluate the device-level impact of our enhanced DSP block by comparing systolic array matrix multiplier implementations across all MXFP precisions, contrasting the best-available strategies on the existing architecture against designs leveraging our modified DSP block. Our results demonstrate an average throughput improvement of 4.2x across all supported MXFP formats.

cs.AR↗

arXiv2026

Boosting FPGA Performance with Direct BRAM-DSP Paths

Efficient data movement between memory and compute units is a key performance bottleneck in modern FPGA designs, particularly for deep learning (DL) workloads. In typical FPGA architectures, data transfers between block RAMs (BRAMs) and digital signal processing units (DSPs) must traverse the global routing network, leading to increased wirelength, routing congestion, and critical-path delays. Prior work has explored in- and near-BRAM compute architectures to mitigate these issues, but such solutions often require fundamental changes to FPGA architecture and CAD tools, limiting their commercial viability. This paper proposes a lightweight architectural enhancement that introduces a dedicated direct connection between BRAM and DSP blocks, enabling BRAM data to be consumed by DSPs without passing through the global interconnect. We also enhance the placement algorithm to recognize these BRAM-DSP macro blocks. The proposed architectural change incurs negligible area and delay overhead and does not affect non-DL benchmarks, while the proposed CAD remains compatible with the baseline architecture, where it yields negligible change in quality-of-results (QoR). On an Agilex-10-like FPGA, the proposed architecture and CAD updates deliver up to +25% Fmax and -49% wirelength on common DL layer designs.

cs.AR↗

arXiv2026

Modeling, Optimizing and Exploring Multi-Die FPGA Routing Architectures

Die stacking has enabled 2.5D FPGAs by integrating multiple active dice on a passive silicon interposer for improved yield and capacity, and paved the way for 3D architectures that stack active dice directly atop one another. In these multi-die devices, the unique electrical and physical characteristics of the underlying die-stacking technology impose limitations on inter-die connection density and latency, necessitating a bespoke inter-die routing architecture. However, the absence of accurate and versatile modeling tools has left most questions about how to best design the inter-die routing architecture unanswered. To address this gap, we enhance the open-source FPGA CAD tool VTR to flexibly model a wide range of multi-die routing architectures, and augment VPR's placement and routing engines to improve optimization for both 2.5D and 3D FPGAs. We perform HSPICE-based circuit modeling of inter-die connections for active dice using a 7 nm process node and a 45 nm silicon interposer across several die-crossing technologies. Using this enhanced framework, we conduct a detailed design space exploration of inter-die routing architecture in 2.5D and 3D FPGAs, characterizing the impact of die-crossing technology, inter-die connection count, fan-in/fan-out, and interposer wire length on critical path delay (CPD), wirelength, area, and routability. Our results show that with suitable inter-die routing architectures, 2.5D and 3D FPGAs can increase capacity without significant routability or delay penalties. Specifically, 3D FPGAs achieve up to 14% wirelength reduction and 6% CPD improvement over 2D devices, and remain routable even with existing $10\,\mu$m pitch technologies, while 2.5D FPGAs incur only a 2% wirelength and 4% CPD overhead at 32% inter-die connectivity. All extensions are open source and integrated with the VTR master branch.

cs.AR↗

arXiv2026

D\'ej\`a Vu Packing: Optimizing FPGA Logic Clustering Runtime via Pattern Memoization

Implementing a digital circuit on an FPGA fabric requires clustering technology-mapped netlist primitives into coarser-granularity blocks that can be directly mapped to the physical resources available on the FPGA. As the architecture of FPGA logic blocks (LBs) has grown in complexity, with sophisticated logic elements (LEs) and highly irregular local interconnect, this packing problem has become more challenging. To ensure the feasibility of intracluster routing, the computer-aided design (CAD) tools must solve a costly multi-source multi-sink routing problem for each candidate cluster. In this paper, we first show that such packing legality checks consume a significant portion of the CAD flow runtime for LB architectures with complex LEs and local routing structures resembling modern commercial FPGAs. We demonstrate that the packing stage constitutes 58% and 94% of the entire Versatile Place and Route (VPR) flow runtime on average when mapping a wide variety of benchmarks to the AMD 7-series-like and Altera Stratix-10-like VTR architecture captures, respectively. By analyzing the packing algorithm behavior, we observe that a significant fraction of the attempted packed clusters are repetitions of a much smaller number of packing patterns, and therefore many of the packing legality checks are redundant and could be skipped. To this end, we introduce our D\'ej\`a Vu packing approach, which leverages a novel packing signature tree data structure that enables efficient identification of recurring packing patterns and memoization of their legality check outcomes. Our approach speeds up the packing by up to 13.4x and 29.3x, with an average of 3.7x and 6.9x, across the evaluated benchmarks on the 7-series and Stratix 10 architectures. These packing runtime gains result in a significant 1.6x and 5.3x average reduction in end-to-end VPR runtime, while maintaining quality of results.

cs.AR↗

arXiv2025

Double Duty: FPGA Architecture to Enable Concurrent LUT and Adder Chain Usage

Flexibility and customization are key strengths of Field-Programmable Gate Arrays (FPGAs) when compared to other computing devices. For instance, FPGAs can efficiently implement arbitrary-precision arithmetic operations, and can perform aggressive synthesis optimizations to eliminate ineffectual operations. Motivated by sparsity and mixed-precision in deep neural networks (DNNs), we investigate how to optimize the current logic block architecture to increase its arithmetic density. We find that modern FPGA logic block architectures prevent the independent use of adder chains, and instead only allow adder chain inputs to be fed by look-up table (LUT) outputs. This only allows one of the two primitives -- either adders or LUTs -- to be used independently in one logic element and prevents their concurrent use, hampering area optimizations. In this work, we propose the Double Duty logic block architecture to enable the concurrent use of the adders and LUTs within a logic element. Without adding expensive logic cluster inputs, we use 4 of the existing inputs to bypass the LUTs and connect directly to the adder chain inputs. We accurately model our changes at both the circuit and CAD levels using open-source FPGA development tools. Our experimental evaluation on a Stratix-10-like architecture demonstrates area reductions of 21.6% on adder-intensive circuits from the Kratos benchmarks, and 9.3% and 8.2% on the more general Koios and VTR benchmarks respectively. These area improvements come without an impact to critical path delay, demonstrating that higher density is feasible on modern FPGA architectures by adding more flexibility in how the adder chain is used. Averaged across all circuits from our three evaluated benchmark set, our Double Duty FPGA architecture improves area-delay product by 9.7%.

cs.AR↗

arXiv2024

Field-Programmable Gate Array Architecture for Deep Learning: Survey & Future Directions

Deep learning (DL) is becoming the cornerstone of numerous applications both in datacenters and at the edge. Specialized hardware is often necessary to meet the performance requirements of state-of-the-art DL models, but the rapid pace of change in DL models and the wide variety of systems integrating DL make it impossible to create custom computer chips for all but the largest markets. Field-programmable gate arrays (FPGAs) present a unique blend of reprogrammability and direct hardware execution that make them suitable for accelerating DL inference. They offer the ability to customize processing pipelines and memory hierarchies to achieve lower latency and higher energy efficiency compared to general-purpose CPUs and GPUs, at a fraction of the development time and cost of custom chips. Their diverse high-speed IOs also enable directly interfacing the FPGA to the network and/or a variety of external sensors, making them suitable for both datacenter and edge use cases. As DL has become an ever more important workload, FPGA architectures are evolving to enable higher DL performance. In this article, we survey both academic and industrial FPGA architecture enhancements for DL. First, we give a brief introduction on the basics of FPGA architecture and how its components lead to strengths and weaknesses for DL applications. Next, we discuss different styles of DL inference accelerators on FPGA, ranging from model-specific dataflow styles to software-programmable overlay styles. We survey DL-specific enhancements to traditional FPGA building blocks such as logic blocks, arithmetic circuitry, and on-chip memories, as well as new in-fabric DL-specialized blocks for accelerating tensor computations. Finally, we discuss hybrid devices that combine processors and coarse-grained accelerator blocks with FPGA-like interconnect and networks-on-chip, and highlight promising future research directions.

cs.AR↗

arXiv2023

RAD-Sim: Rapid Architecture Exploration for Novel Reconfigurable Acceleration Devices

With the continued growth in field-programmable gate array (FPGA) capacity and their incorporation into new environments such as datacenters, we have witnessed the introduction of a new class of reconfigurable acceleration devices (RADs) that go beyond conventional FPGA architectures. These devices combine a reconfigurable fabric with coarse-grained domain-specialized accelerator blocks all connected via a high-performance packet-switched network-on-chip (NoC) for efficient system-wide communication. However, we lack the tools necessary to efficiently explore the huge design space for RADs, study the complex interactions between their different components and evaluate various combinations of design choices. In this work, we develop RAD-Sim, a cycle-level architecture simulator that allows rapid application-driven exploration of the design space of novel RADs. To showcase the capabilities of RADSim, we map and simulate a state-of-the-art deep learning (DL) inference overlay on a RAD instance incorporating an FPGA fabric and a complex of hard matrix-vector multiplication engines, communicating over a system-wide NoC. Through this example, we show how RAD-Sim can help architects quantify the effect of changing specific architecture parameters on end-to-end application performance.

cs.AR↗

arXiv2022

Neighbors From Hell: Voltage Attacks Against Deep Learning Accelerators on Multi-Tenant FPGAs

Field-programmable gate arrays (FPGAs) are becoming widely used accelerators for a myriad of datacenter applications due to their flexibility and energy efficiency. Among these applications, FPGAs have shown promising results in accelerating low-latency real-time deep learning (DL) inference, which is becoming an indispensable component of many end-user applications. With the emerging research direction towards virtualized cloud FPGAs that can be shared by multiple users, the security aspect of FPGA-based DL accelerators requires careful consideration. In this work, we evaluate the security of DL accelerators against voltage-based integrity attacks in a multitenant FPGA scenario. We first demonstrate the feasibility of such attacks on a state-of-the-art Stratix 10 card using different attacker circuits that are logically and physically isolated in a separate attacker role, and cannot be flagged as malicious circuits by conventional bitstream checkers. We show that aggressive clock gating, an effective power-saving technique, can also be a potential security threat in modern FPGAs. Then, we carry out the attack on a DL accelerator running ImageNet classification in the victim role to evaluate the inherent resilience of DL models against timing faults induced by the adversary. We find that even when using the strongest attacker circuit, the prediction accuracy of the DL accelerator is not compromised when running at its safe operating frequency. Furthermore, we can achieve 1.18-1.31x higher inference performance by over-clocking the DL accelerator without affecting its prediction accuracy.

cs.CR↗

arXiv2022

FPGA-based AI Smart NICs for Scalable Distributed AI Training Systems

Rapid advances in artificial intelligence (AI) technology have led to significant accuracy improvements in a myriad of application domains at the cost of larger and more compute-intensive models. Training such models on massive amounts of data typically requires scaling to many compute nodes and relies heavily on collective communication algorithms, such as all-reduce, to exchange the weight gradients between different nodes. The overhead of these collective communication operations in a distributed AI training system can bottleneck its performance, with more pronounced effects as the number of nodes increases. In this paper, we first characterize the all-reduce operation overhead by profiling distributed AI training. Then, we propose a new smart network interface card (NIC) for distributed AI training systems using field-programmable gate arrays (FPGAs) to accelerate all-reduce operations and optimize network bandwidth utilization via data compression. The AI smart NIC frees up the system's compute resources to perform the more compute-intensive tensor operations and increases the overall node-to-node communication efficiency. We perform real measurements on a prototype distributed AI training system comprised of 6 compute nodes to evaluate the performance gains of our proposed FPGA-based AI smart NIC compared to a baseline system with regular NICs. We also use these measurements to validate an analytical model that we formulate to predict performance when scaling to larger systems. Our proposed FPGA-based AI smart NIC enhances overall training performance by 1.6x at 6 nodes, with an estimated 2.5x performance improvement at 32 nodes, compared to the baseline system using conventional NICs.

cs.DC↗

arXiv2021

Koios: A Deep Learning Benchmark Suite for FPGA Architecture and CAD Research

With the prevalence of deep learning (DL) in many applications, researchers are investigating different ways of optimizing FPGA architecture and CAD to achieve better quality-of-results (QoR) on DL-based workloads. In this optimization process, benchmark circuits are an essential component; the QoR achieved on a set of benchmarks is the main driver for architecture and CAD design choices. However, current academic benchmark suites are inadequate, as they do not capture any designs from the DL domain. This work presents a new suite of DL acceleration benchmark circuits for FPGA architecture and CAD research, called Koios. This suite of 19 circuits covers a wide variety of accelerated neural networks, design sizes, implementation styles, abstraction levels, and numerical precisions. These designs are larger, more data parallel, more heterogeneous, more deeply pipelined, and utilize more FPGA architectural features compared to existing open-source benchmarks. This enables researchers to pin-point architectural inefficiencies for this class of workloads and optimize CAD tools on more realistic benchmarks that stress the CAD algorithms in different ways. In this paper, we describe the designs in our benchmark suite, present results of running them through the Verilog-to-Routing (VTR) flow using a recent FPGA architecture model, and identify key insights from the resulting metrics. On average, our benchmarks have 3.7x more netlist primitives, 1.8x and 4.7x higher DSP and BRAM densities, and 1.7x higher frequency with 1.9x more near-critical paths compared to the widely-used VTR suite. Finally, we present two example case studies showing how architectural exploration for DL-optimized FPGAs can be performed using our new benchmark suite.

cs.AR↗