Karthik Swaminathan

dblp:13/3711 · DBLP profile ↗
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32ranked-venue papers
7as first author
13since 2021 · last 2026
0000-0002-4799-7587ORCID · corroborated

Domains — the database's venue-derived domains; a paper can count in several

Systems, architecture and hardware · 32 · 7 first-author · 13 since 2021Software engineering, systems software and programming languages · 7 · 2 first-author · 4 since 2021Artificial intelligence and machine learning · 2 · 2 since 2021Security and privacy · 2 · 1 since 2021Applied, interdisciplinary, general and emerging computing · 2 · 2 first-author
YearPublicationVenuePosition
2026 FortiSky: Enhancing Adversarial and Bit-Error Robustness for Efficient and Secure Autonomous Systems
Zishen Wan, Karthik Swaminathan, Nandhini Chandramoorthy, Tushar Krishna, Vijay Janapa Reddi, Arijit Raychowdhury
DATE2
2026 One Error to Rule Them All: Can a Single Bit-Flip Disrupt Fully Homomorphic Encryption?
Vattana Chan, Matías Mazzanti, Karthik Swaminathan, Augusto Vega, Esteban E. Mocskos, Radha Venkatagiri
DSN3
2025 No Time to Lose: Enabling Real-Time Fluorescence Lifetime Imaging on Resource-constrained FPGAs Through Efficient Scheduling
abstract
Fluorescence lifetime imaging (FLI) is a widely used technique in the biomedical field for measuring the decay times of fluorescent molecules, providing insights into metabolic states, protein interactions, and ligand-receptor bindings [1, 5]. However, its broader application in fast biological processes, such as dynamic activity monitoring, and clinical use, such as in guided surgery, is limited by long data acquisition times and computationally demanding data processing. While deep learning has reduced post-processing times, time-resolved data acquisition remains a bottleneck for real-time applications. To address this,we propose a method to achieve near realtime FLI using an FPGA-based hardware accelerator. Specifically,we implemented a GRU-based sequence-to-sequence (Seq2Seq) model [3] on an FPGA board compatible with time-resolved cameras. The GRU model balances accurate processing with the resource constraints of FPGAs, which have limited DSP units and BRAM. The limited memory and computational resources on the FPGA require efficient scheduling of operations and memory allocation to deploy deep learning models for low-latency applications.We address these challenges by using STOMP, a queue-based discrete-event simulator that automates and optimizes task scheduling and memory management on hardware [4]. By integrating a GRU-based Seq2Seq model and its compressed version, called Seq2SeqLite [2], generated through knowledge distillation (KD), we were able to process multiple pixels in parallel, reducing latency compared to sequential processing. We explore various levels of parallelism to achieve an optimal balance between performance and resource utilization. Our results indicate that the proposed techniques achieved a 17.7x and 52.0x speedup over manual scheduling for the Seq2Seq model and the Seq2SeqLite model, respectively. Furthermore, the Seq2SeqLite model achieved a 98% reduction in parameters compared to the Seq2Seq model.
Ismail Erbas, Aporva Amarnath, Vikas Pandey, Karthik Swaminathan, Naigang Wang, Xavier Intes
FPGA4
2025 FHENDI: A Near-DRAM Accelerator for Compiler-Generated Fully Homomorphic Encryption Applications
abstract
Fully homomorphic encryption (FHE) is a powerful cryptographic technique that enables computation on encrypted data without needing to decrypt it. It has broad applications in scenarios where sensitive data needs to be processed in the cloud or in other untrusted environments. FHE applications are both compute- and memory-intensive, owing to expensive operations on large data. While prior works address the challenges of efficient compute using dedicated hardware, expensive memory transfers still remain a major limiting factor. In this work, we propose a hierarchical near-DRAM processing (NDP) solution for FHE applications, called FHENDI, that harnesses the massive DRAM bank bandwidth. We observe various data access patterns in FHE that reveal distinct levels of parallelism: element-wise, limb-wise, coefficient-wise, and ciphertext-wise. FHENDI exploits these levels of parallelism to map FHE operations and data onto different hierarchies of our design, while addressing three major challenges with NDP for FHE: (i) the lack of bank-to-bank communication support, (ii) limited die-to-die bandwidth, and (iii) large memory access latencies. We resolve the first problem through a novel, conflict-free mapping algorithm built atop localized permutation networks that enables efficient element-wise and butterfly operations in FHE. The second problem is addressed by pipelining the execution of parallel bootstrap operations observed in compiled FHE workloads. Finally, we hide the memory access latency behind computation latency by exploiting a dual-banking scheme and subarray-level parallelism (SLP) of the DRAM banks. We evaluate FHENDI using representative workloads in the domains of privacy-preserving machine learning inference on CNNs and Transformers, database range query, and sorting, that are obtained using a compiler framework called HElayers. We compare FHENDI with a server-class CPU and GPU running the state-of-the-art HEaaN library, and an FHE accelerator ASIC, and report mean speedups of $2145.8 \times, 118.29 \times$, and $2.45 \times$, respectively.
Yongmo Park, Aporva Amarnath, Subhankar Pal, Karthik Swaminathan, Alper Buyuktosunoglu, Hayim Shaul, Ehud Aharoni, Nir Drucker, Wei Lu 0003, Omri Soceanu, Pradip Bose
HPCA4
2025 AdaptBot: Combining LLM with Knowledge Graphs and Human Input for Generic-to-Specific Task Decomposition and Knowledge Refinement
abstract
An embodied agent assisting humans is often asked to complete new tasks, and there may not be sufficient time or labeled examples to train the agent to perform these new tasks. Large Language Models (LLMs) trained on considerable knowledge across many domains can be used to predict a sequence of abstract actions for completing such tasks, although the agent may not be able to execute this sequence due to task-, agent-, or domain-specific constraints. Our framework addresses these challenges by leveraging the generic predictions provided by LLM and the prior domain knowledge encoded in a Knowledge Graph (KG), enabling an agent to quickly adapt to new tasks. The robot also solicits and uses human input as needed to refine its existing knowledge. Based on experimental evaluation in the context of cooking and cleaning tasks in simulation domains, we demonstrate that the interplay between LLM, KG, and human input leads to substantial performance gains compared with just using the LLM. Project website1§Project supported in part by TCS Research India: https://sssshivvvv.github.io/adaptbot/
Shivam Singh, Karthik Swaminathan, Nabanita Dash, Snehasis Banerjee, Mohan Sridharan, K. Madhava Krishna
ICRA2
2024 MulBERRY: Enabling Bit-Error Robustness for Energy-Efficient Multi-Agent Autonomous Systems
abstract
The adoption of autonomous swarms, consisting of a multitude of unmanned aerial vehicles (UAVs), operating in a collaborative manner, has become prevalent in mainstream application domains for both military and civilian purposes. These swarms are expected to collaboratively carry out navigation tasks and employ complex reinforcement learning (RL) models within the stringent onboard size, weight, and power constraints. While techniques such as reducing onboard operating voltage can improve the energy efficiency of both computation and flight missions, they can lead to on-chip bit failures that are detrimental to mission safety and performance.
Zishen Wan, Nandhini Chandramoorthy, Karthik Swaminathan, Kshitij Bhardwaj, Vijay Janapa Reddi, Arijit Raychowdhury
ASPLOS (2)3
2024 Anticipate & Act: Integrating LLMs and Classical Planning for Efficient Task Execution in Household Environments†
abstract
Assistive agents performing household tasks such as making the bed or cooking breakfast often compute and execute actions that accomplish one task at a time. However, efficiency can be improved by anticipating upcoming tasks and computing an action sequence that jointly achieves these tasks. State-of-the-art methods for task anticipation use data-driven deep networks and Large Language Models (LLMs), but they do so at the level of high-level tasks and/or require many training examples. Our framework leverages the generic knowledge of LLMs through a small number of prompts to perform high-level task anticipation, using the anticipated tasks as goals in a classical planning system to compute a sequence of finer-granularity actions that jointly achieve these goals. We ground and evaluate our framework’s abilities in realistic scenarios in the VirtualHome environment and demonstrate a 31% reduction in execution time compared with a system that does not consider upcoming tasks.
Raghav Arora, Shivam Singh, Karthik Swaminathan, Ahana Datta, Snehasis Banerjee, Brojeshwar Bhowmick, Krishna Murthy Jatavallabhula, Mohan Sridharan, K. Madhava Krishna
ICRA3
2024 BlitzCoin: Fully Decentralized Hardware Power Management for Accelerator-Rich SoCs
abstract
On-chip power-management techniques have evolved over several processor generations. However, response time and scalability constraints have made it difficult to translate existing power-management strategies to current or next-generation System-on-Chip (SoC) architectures, which are expected to comprise tens to hundreds of cores and accelerators. In this work we present BlitzCoin, a fully decentralized hardware power-management strategy for large, accelerator-rich SoCs, coupled with optimized unified voltage and frequency regulation. We evaluated BlitzCoin through RTL simulations of multiple SoCs targeted toward different application domains. The results are further validated through silicon measurements of a fabricated 12 nm many-accelerator SoC that includes BlitzCoin. Our evaluations show that BlitzCoin is markedly faster, with 8× to 12× lower response times, which provides 25%-34% throughput improvement and allows for scaling to 7 × to 13 × larger SoCs compared to state-of-the-art centralized power-management strategies, all with an area overhead of <1%.
Martin Cochet, Karthik Swaminathan, Erik Jens Loscalzo, Joseph Zuckerman, Maico Cassel, Davide Giri, Alper Buyuktosunoglu, David Brooks 0001, Gu-Yeon Wei, Kenneth L. Shepard, Luca P. Carloni, Pradip Bose
ISCA2
2023 BERRY: Bit Error Robustness for Energy-Efficient Reinforcement Learning-Based Autonomous Systems
abstract
Autonomous systems, such as Unmanned Aerial Vehicles (UAVs), are expected to run complex reinforcement learning (RL) models to execute fully autonomous position-navigation-time tasks within stringent onboard weight and power constraints. We observe that reducing onboard operating voltage can benefit the energy efficiency of both the computation and flight mission, however, it can also result in on-chip bit failures that are detrimental to mission safety and performance. To this end, we propose BERRY, a robust learning framework to improve bit error robustness and energy efficiency for RL-enabled autonomous systems. BERRY supports robust learning, both offline and on-board the UAV, and for the first time, demonstrates the practicality of robust low-voltage operation on UAVs that leads to high energy savings in both compute-level operation and system-level quality-of-flight. We perform extensive experiments on 72 autonomous navigation scenarios and demonstrate that BERRY generalizes well across environments, UAVs, autonomy policies, operating voltages and fault patterns, and consistently improves robustness, efficiency and mission performance, achieving up to 15.62% reduction in flight energy, 18.51% increase in the number of successful missions, and 3.43× processing energy reduction.
Zishen Wan, Nandhini Chandramoorthy, Karthik Swaminathan, Vijay Janapa Reddi, Arijit Raychowdhury
DAC3
2022 A Scalable Methodology for Agile Chip Development with Open-Source Hardware Components
abstract
We present a scalable methodology for the agile physical design of tile-based heterogeneous system-on-chip (SoC) architectures that simplifies the reuse and integration of open-source hardware components. The methodology leverages the regularity of the on-chip communication infrastructure, which is based on a multi-plane network-on-chip (NoC), and the modularity of socket interfaces, which connect the tiles to the NoC. Each socket also provides its tile with a set of platform services, including independent clocking and voltage control. As a result, the physical design of each tile can be decoupled from its location in the top-level floorplan of the SoC and the overall SoC design can benefit from a hierarchical timing-closure flow, design reuse and, if necessary, fast respin. With the proposed methodology we completed two SoC tapeouts of increasing complexity, which illustrate its capabilities and the resulting gains in terms of design productivity.
Maico Cassel, Martin Cochet, Karthik Swaminathan, Joseph Zuckerman, Paolo Mantovani, Davide Giri, Jeff Zhang 0001, Erik Jens Loscalzo, Gabriele Tombesi, Kevin Tien, Nandhini Chandramoorthy, John-David Wellman, David Brooks 0001, Gu-Yeon Wei, Kenneth L. Shepard, Luca P. Carloni, Pradip Bose
ICCAD4
2022 Analyzing and Improving Resilience and Robustness of Autonomous Systems
abstract
Autonomous systems have reached a tipping point, with a myriad of self-driving cars, unmanned aerial vehicles (UAVs), and robots being widely applied and revolutionizing new applications. The continuous deployment of autonomous systems reveals the need for designs that facilitate increased resiliency and safety. The ability of an autonomous system to tolerate, or mitigate against errors, such as environmental conditions, sensor, hardware and software faults, and adversarial attacks, is essential to ensure its functional safety. Application-aware resilience metrics, holistic fault analysis frameworks, and lightweight fault mitigation techniques are being proposed for accurate and effective resilience and robustness assessment and improvement. This paper explores the origination of fault sources across the computing stack of autonomous systems, discusses the various fault impacts and fault mitigation techniques of different scales of autonomous systems, and concludes with challenges and opportunities for assessing and building next-generation resilient and robust autonomous systems.
Zishen Wan, Karthik Swaminathan, Nandhini Chandramoorthy, Arijit Raychowdhury
ICCAD2
2021 Crossbar based Processing in Memory Accelerator Architecture for Graph Convolutional Networks
abstract
Graph data structures are central to many applications such as social networks, citation networks, molecular interactions, and navigation systems. Graph Convolutional Networks (GCNs) are used to process and learn insights from the graph data for tasks such as link prediction, node classification, and learning node embeddings. The compute and memory access characteristics of GCNs differ, both from conventional graph analytics algorithms and from convolutional neural networks, rendering the existing accelerators for graph analytics as well as deep learning, inefficient. In this work, we propose PIM-GCN, a crossbar-based processing-in-memory (PIM) accelerator architecture for GCNs. PIM-GCN incorporates a node-stationary dataflow with support for both Compressed Sparse Row (CSR) and Compressed Sparse Column (CSC) graph data representations. We propose techniques for graph traversal in the compressed sparse domain, feature aggregation, and feature transformation operations in GCNs mapped to in-situ analog compute functions of crossbar memory, and present the trade-offs in performance, energy, and scalability aspects of the PIM-GCN architecture for CSR, and CSC graph data representations. PIM-GCN shows an average speedup of over$3-16\times$and an average energy reduction of$4-12\times$compared to the existing accelerator architectures.
Nagadastagiri Challapalle, Karthik Swaminathan, Nandhini Chandramoorthy, Narayanan Vijaykrishnan
ICCAD2
2021 Energy Efficiency Boost in the AI-Infused POWER10 Processor
abstract
We present the novel micro-architectural features, supported by an innovative and novel pre-silicon methodology in the design of POWER10. The resulting projected energy efficiency boost over POWER9 is 2.6x at core level (for SPECint) and up to 3x at socket level. In addition, a new feature supporting inline AI acceleration was added to the POWER ISA and incorporated into the POWER10 processor core design. The resulting boost in SIMD/AI socket performance is projected to be up to 10x for FP32 and 21x for INT8 models of ResNet-50 and BERT-Large. In this paper, we describe the novel methodology deployed and used not only to obtain these efficiency boosts for traditional workloads, but also to infuse AI/ML/HPC capability directly into the POWER10 core.
Brian W. Thompto, Dung Q. Nguyen, José E. Moreira, Ramon Bertran Monfort, Hans M. Jacobson, Richard J. Eickemeyer, Rahul M. Rao, Michael Goulet, Marcy Byers, Christopher J. Gonzalez, Karthik Swaminathan, Nagu R. Dhanwada, Silvia M. Müller, Satish Kumar Sadasivam, Robert K. Montoye, William J. Starke, Christian G. Zoellin, Michael S. Floyd, Jeffrey Stuecheli, Nandhini Chandramoorthy, John-David Wellman, Alper Buyuktosunoglu, Matthias Pflanz, Balaram Sinharoy, Pradip Bose
ISCA11
2020 GaaS-X: Graph Analytics Accelerator Supporting Sparse Data Representation using Crossbar Architectures
abstract
Graph analytics applications are ubiquitous in this era of a connected world. These applications have very low compute to byte-transferred ratios and exhibit poor locality, which limits their computational efficiency on general purpose computing systems. Conventional hardware accelerators employ custom dataflow and memory hierarchy organization to overcome these challenges. Processing-in-memory (PIM) accelerators leverage massively parallel compute capable memory arrays to perform the in-situ operations on graph data or employ custom compute elements near the memory to leverage larger internal bandwidths. In this work, we present GaaS-X, a graph analytics accelerator that inherently supports the sparse graph data representations using an in-situ compute-enabled crossbar memory architectures. We alleviate the overheads of redundant writes, sparse to dense conversions, and redundant computations on the invalid edges that are present in the state of the art crossbar-based PIM accelerators. GaaS-X achieves 7.7× and 2.4× performance and 22× and 5.7×, energy savings, respectively, over two state-of-the-art crossbar accelerators and offers orders of magnitude improvements over GPU and CPU solutions.
Nagadastagiri Challapalle, Sahithi Rampalli, Linghao Song, Nandhini Chandramoorthy, Karthik Swaminathan, Jack Sampson, Yiran Chen 0001, Narayanan Vijaykrishnan
ISCA5
2020 Guest Editorial: IEEE TC Special Issue on Domain-Specific Architectures for Emerging Applications
abstract
The papers in this special section examine domain-specific architectures for emerging applications. Presents innovative research in domain-specific architectures across a broad range of emerging applications.
Lisa Wu Wills, Karthik Swaminathan
IEEE Trans. Computers2
2019 Resilient Low Voltage Accelerators for High Energy Efficiency
abstract
Low voltage architecture and design are key enablers of high throughput per watt in heterogeneous, accelerator-rich many-core designs. However, such low voltage operation poses significant challenges because of difficulties in achieving reliable functionality of on-chip memories, particularly SRAMs at these design points. In this paper, we present a technique of low-voltage neural network acceleration, where the embedded SRAM architecture is equipped with a novel application-aware supply voltage boosting capability. This technique mitigates low-voltage induced failures, while enabling Very low voltage (VLV)1operation during most of the application run, resulting in substantial improvement in net energy efficiency. We present a framework to evaluate the impact of low-voltage SRAM errors on machine learning applications and characterize trade-offs between output inference accuracy and energy efficiency in our application-programmable supply boosted SRAM architecture. Using the proposed technique we push the limits on the minimum operable voltage (Vmin) for the desired output quality. As a proof of concept, we demonstrate these techniques on Dante, a Deep Neural Network (DNN) accelerator chip taped out in state-of-the art 14nm technology.
Nandhini Chandramoorthy, Karthik Swaminathan, Martin Cochet, Arun Paidimarri, Schuyler Eldridge, Rajiv V. Joshi, Matthew M. Ziegler, Alper Buyuktosunoglu, Pradip Bose
HPCA2
2018 Impact of Software Approximations on the Resiliency of a Video Summarization System
abstract
In this work, we examine the resiliency of a state-of-the-art end-to-end video summarization (VS) application that serves as a representative emerging workload in the domain of real time edge computing. The VS application constitutes key video and image analytic elements that are processed by embedded systems aboard unmanned aerial vehicles (UAVs). Real-time performance and energy constraints motivate the consideration of approximations to the VS algorithm. However, mission-critical UAV applications also demand stringent levels of resilience to soft errors that are exacerbated with higher altitude. In this work, we study the effects of three different types of software approximations on the application level resiliency (to soft errors) of the VS algorithm. We show that our approximations yield significant energy savings (up to 68%), with commensurate improvement in performance, without a degradation in the application resilience. Further, by proposing a novel quality metric (appropriate for the UAV vision analytics domain) for the summarized video output, we show that even though the rate of Silent Data Corruptions (SDCs) increases slightly (<2%), the impact of these SDCs on output quality is limited. Thus, we conclude that software approximation can be utilized to achieve significant gains in performance and energy without affecting application resiliency.
Radha Venkatagiri, Karthik Swaminathan, Chung-Ching Lin, Liang Wang 0055, Alper Buyuktosunoglu, Pradip Bose, Sarita V. Adve
DSN2
2017 BRAVO: Balanced Reliability-Aware Voltage Optimization
abstract
Defining a processor micro-architecture for a targeted productspace involves multi-dimensional optimization across performance, power and reliability axes. A key decision in sucha definition process is the circuit-and technology-driven parameterof the nominal (voltage, frequency) operating point. This is a challenging task, since optimizing individually orpair-wise amongst these metrics usually results in a designthat falls short of the specification in at least one of the threedimensions. Aided by academic research, industry has nowadopted early-stage definition methodologies that considerboth energy-and performance-related metrics. Reliabilityrelatedenhancements, on the other hand, tend to get factoredin via a separate thread of activity. This task is typically pursuedwithout thorough pre-silicon quantifications of the energyor even the performance cost. In the late-CMOS designera, reliability needs to move from a post-silicon afterthoughtor validation-only effort to a pre-silicon definitionprocess. In this paper, we present BRAVO, a methodologyfor such reliability-aware design space exploration. BRAVOis supported by a multi-core simulation framework that integratesperformance, power and reliability modeling capability. Errors induced by both soft and hard fault incidence arecaptured within the reliability models. We introduce the notionof the Balanced Reliability Metric (BRM), that we useto evaluate overall reliability of the processor across soft andhard error incidences. We demonstrate up to 79% improvementin reliability in terms of this metric, for only a 6% dropin overall energy efficiency over design points that maximizeenergy efficiency. We also demonstrate several real-life usecaseapplications of BRAVO in an industrial setting.
Karthik Swaminathan, Nandhini Chandramoorthy, Chen-Yong Cher, Ramon Bertran Monfort, Alper Buyuktosunoglu, Pradip Bose
HPCA1
2017 Very Low Voltage (VLV) Design
abstract
This paper is a tutorial-style introduction to a special session on: Effective Voltage Scaling in the Late CMOS Era. It covers the fundamental challenges and associated solution strategies in pursuing very low voltage (VLV) designs. We discuss the performance and system reliability constraints that are key impediments to VLV. The associated trade-offs across power, performance and reliability are helpful in inferring the optimal operational voltage-frequency point. This work was performed under the auspices of an ongoing DARPA program (named PERFECT) that is focused on maximizing system-level energy efficiency.
Ramon Bertran Monfort, Pradip Bose, David Brooks 0001, Jeff Burns, Alper Buyuktosunoglu, Nandhini Chandramoorthy, Eric Cheng, Martin Cochet, Schuyler Eldridge, Daniel J. Friedman, Hans M. Jacobson, Rajiv V. Joshi, Subhasish Mitra, Robert K. Montoye, Arun Paidimarri, Pritish Parida, Kevin Skadron, Mircea R. Stan, Karthik Swaminathan, Augusto Vega, Swagath Venkataramani, Christos Vezyrtzis, Gu-Yeon Wei, John-David Wellman, Matthew M. Ziegler
ICCD19
2017 Dynamic Power and Energy Management for Energy Harvesting Nonvolatile Processor Systems
abstract
Self-powered systems running on scavenged energy will be a key enabler for pervasive computing across the Internet of Things. The variability of input power in energy-harvesting systems limits the effectiveness of static optimizations aimed at maximizing the input-energy-to-computation ratio. We show that the resultant gap between available and exploitable energy is significant, and that energy storage optimizations alone do not significantly close the gap. We characterize these effects on a real, fabricated energy-harvesting system based on a nonvolatile processor. We introduce a unified energy-oriented approach to first optimize the number of backups, by more aggressively using the stored energy available when power failure occurs, and then optimize forward progress via improving the rate of input energy to computation via dynamic voltage and frequency scaling and self-learning techniques. We evaluate combining these schemes and show capture of up to 75.5% of all input energy toward processor computation, an average of 1.54 × increase over the best static “Forward Progress” baseline system. Notably, our energy-optimizing policy combinations simultaneously improve both the rate of forward progress and the rate of backup events (by up to 60.7% and 79.2% for RF power, respectively, and up to 231.2% and reduced to zero, respectively, for solar power). This contrasts with static frequency optimization approaches in which these two metrics are antagonistic.
Kaisheng Ma, Xueqing Li 0002, Huichu Liu, Xiao Sheng, Karthik Swaminathan, Yongpan Liu, Yuan Xie 0001, Jack Sampson, Narayanan Vijaykrishnan
ACM Trans. Embed. Comput. Syst.6
2015 Architecture exploration for ambient energy harvesting nonvolatile processors
abstract
Energy harvesting has been widely investigated as a promising method of providing power for ultra-low-power applications. Such energy sources include solar energy, radio-frequency (RF) radiation, piezoelectricity, thermal gradients, etc. However, the power supplied by these sources is highly unreliable and dependent upon ambient environment factors. Hence, it is necessary to develop specialized systems that are tolerant to this power variation, and also capable of making forward progress on the computation tasks. The simulation platform in this paper is calibrated using measured results from a fabricated nonvolatile processor and used to explore the design space for a nonvolatile processor with different architectures, different input power sources, and policies for maximizing forward progress.
Kaisheng Ma, Shuangchen Li, Karthik Swaminathan, Xueqing Li 0002, Yongpan Liu, Jack Sampson, Yuan Xie 0001, Narayanan Vijaykrishnan
HPCA4
2015 Resilient, UAV-embedded real-time computing
abstract
In this paper, we propose a hierarchical computational system architecture to support the target domain of realtime mobile computing in the context of unmanned aerial vehicles (UAVs). The overall architectural vision includes support for system resilience in the presence of uncertainties in the operational environment of surveillance UAVs. We report measurement-based results that are obtained from a UAV proxy demonstration apparatus. The apparatus consists of a Raspberry Pi (RPi) board that serves as an on-board UAV computer, working with support from a laptop that serves as the on-ground computing infrastructure where an operator "consumes" video information received from the UAV. We quantify the gap between the on-board UAV camera frame rate (input) and the on-ground operator-observed frame rate (output) for a specialized class of computer vision applications germane to the UAV-based aerial surveillance domain. The goal is to keep the frame rate observed by the ground operator as close (or ideally equal) to the on-board UAV camera frame rate (i.e. to preserve the real-time aspect) despite the unstable bandwidth availability in the channel connecting both ends. The proposed hierarchical approach significantly outperforms two considered baselines: one in which computation takes place entirely on the UAV computer and another in which computation takes place entirely on the ground. This improved performance is due to a more balanced resource sharing between the on-board UAV computer and UAV-to-ground communication channel. Later, we show how the observed frame rate improves when the RPi board is replaced with an NVIDIA Jetson TK1 board. Based on the observations gleaned from these "proxy" experiments, we sketch the fundamentals of our ongoing work in model-based predictive analysis of resilient "UAV swarm" computational architectures of the future.
Augusto Vega, Chung-Ching Lin, Karthik Swaminathan, Alper Buyuktosunoglu, Sharath Pankanti, Pradip Bose
ICCD3
2015 Resilient mobile cognition: Algorithms, innovations, and architectures
abstract
The importance of the internet-of-things (IOT) is now an established reality. With that backdrop, the phenomenal emergence of cameras/sensors mounted on unmanned aerial, ground and marine vehicles (UAVs, UGVs, UMVs) and body worn cameras is a notable new development. The swarms of cameras and real-time computing thereof are at the heart of new technologies like connected cars, drone-based city-wide surveillance and precision agriculture, etc. Smart computer vision algorithms (with or without dynamic learning) that enable object recognition and tracking, supported by baseline video content summarization or 2D/3D image reconstruction of the scanned environment are at the heart of such new applications. In this article, we summarize our recent innovations in this space. We focus primarily on algorithms and architectural design considerations for video summarization systems.
Raphael Viguier, Chung-Ching Lin, Karthik Swaminathan, Augusto Vega, Alper Buyuktosunoglu, Sharath Pankanti, Pradip Bose, H. Akbarpour, Filiz Bunyak, Kannappan Palaniappan, Guna Seetharaman
ICCD3
2014 Steep Slope Devices: Enabling New Architectural Paradigms
abstract
The existence of domains where traditional CMOS processors are inefficient has been well-documented in the current literature. In particular, the inefficiency of general purpose CMOS designs operating at very low supply voltages is well-known, and steep sub-threshold slope technologies, such as Tunneling Field Effect Transistors (TFETs), have been demonstrated as a viable alternative for the low-voltage operation domain. However, restricting the design space of steep slope technology-based processors to near-threshold or sub-threshold general purpose processors does the technology a disservice.
Karthik Swaminathan, Huichu Liu, Xueqing Li 0002, Moon Seok Kim, Jack Sampson, Narayanan Vijaykrishnan
DAC1
2014 Modeling steep slope devices: From circuits to architectures
abstract
Steep Slope devices, with Heterojunction Tunnel FETs (TFETs) in particular, have been proposed as a viable solution to overcome the subthreshold slope limitation in existing CMOS technology and achieve ultra-low voltage operation with acceptable performance. However, state-of-the-art FinFET technologies continue to demonstrate superior performance than steep slope devices in application domains demanding peak single threaded performance. In this context, we examine different computing paradigms where TFET technologies can be used, not just as a `drop in' replacement, but as an additional parameter to augment the architectural design space. This greatly widens the scope of optimizations for performance and power. We investigate the tradeoffs between device and architectures in general purpose processors when performance, power and temperature are individually constrained. We also synthesize examples of domain-specific accelerators used in computer vision using in-house TFET standard cell libraries to demonstrate the energy benefits of designing TFET-based accelerators. We demonstrate that synthesizing these accelerators using TFETs reduces energy by over 6X in comparison to an equivalent iso-voltage CMOS-based design and by over 30% in comparison to an iso-performance CMOS design.
Karthik Swaminathan, Moon Seok Kim, Nandhini Chandramoorthy, Behnam Sedighi, Robert Perricone, Jack Sampson, Narayanan Vijaykrishnan
DATE1
2014 Refresh Enabled Video Analytics (REVA): Implications on power and performance of DRAM supported embedded visual systems
abstract
Video applications are becoming ubiquitous in mobile and embedded systems. Wearable video systems such as Google Glasses require capabilities for real-time video analytics and prolonged battery lifetimes. Further, the increasing resolution of image sensors in these mobile systems places an increasing demand on both the memory storage as well as the computational power. In this work, we present the Refresh Enabled Video Analytics (REVA) system, an embedded architecture for multi-object scene understanding and tackle the unique opportunities provided by real-time embedded video analytics applications for reducing the DRAM memory refresh energy. We compare our design with the existing design space and show savings of 88% in refresh power and 15% in total power, as compared to a standard DRAM refresh scheme.
Siddharth Advani, Nandhini Chandramoorthy, Karthik Swaminathan, Kevin M. Irick, Yong Cheol Peter Cho, Jack Sampson, Narayanan Vijaykrishnan
ICCD3
2014 An examination of the architecture and system-level tradeoffs of employing steep slope devices in 3D CMPs
abstract
For any given application, there is an optimal throughput point in the space of per-processor performance and the number of such processors given to that application. However, due to thermal, yield, and other constraints, not all of these optimal points can plausibly be constructed with a given technology. In this paper, we look at how emerging steep slope devices, 3D circuit integration, and trends in process technology scaling will combine to shift the boundaries of both attainable performance, and the optimal set of technologies to employ to achieve it. We propose a heterogeneous-technology 3D architecture capable of operating efficiently at an expanded number of points in this larger design space and devise a heterogeneity and thermal aware scheduling algorithm to exploit its potential. Our heterogeneous mapping techniques are capable of producing speedups ranging from 17% for a high end server workloads running at around 90°C to over 160% for embedded systems running below 60°C.
Karthik Swaminathan, Huichu Liu, Jack Sampson, Narayanan Vijaykrishnan
ISCA1
2012 When to forget: A system-level perspective on STT-RAMs
abstract
The benefits of using STT-RAMs as an alternative to SRAMs are being examined in great detail. However their comparatively higher write latencies and energies continue to be roadblocks for migrating to MRAM based technology in memory hierarchies. In this paper, we present a novel method by which we demonstrate significant energy reduction in writing to the STT-RAM cell by relaxing its non-volatility property. We exploit this characteristic for optimizing system-level properties such as garbage collection. By categorizing the objects based on their lifetimes it is possible to tune the data retention time of the STT-RAM to minimize the write energy. Our scheme yielded 37% reduction in dynamic energy, 88% reduction in leakage and 85% improvement in the Energy-Delay Product over a corresponding SRAM based memory structure.
Karthik Swaminathan, Raghav Pisolkar, Cong Xu 0002, Narayanan Vijaykrishnan
ASP-DAC1
2012 Design space exploration of workload-specific last-level caches
abstract
Leakage power of last-level caches constitute a significant part of overall power consumption. Various circuit-level and technology-based methods have been proposed to reduce cache leakage. However, from a system designer's perspective, for a particular configuration and workload, it is not clear which method will be most effective. In this work, we make a detailed evaluation and comparison of cache energy reduction techniques. Our results show that when energy is very scarce and important, the best results are obtained with highly energy efficient Tunnel-FET caches. When the available energy increases and performance becomes a bigger concern, there is no single winner. While a small number of capacity sensitive workloads benefit from increased capacity of STT-RAM caches, latency sensitive workloads prefer solutions with smaller latency penalties such as drowsy caches.
Karthik Swaminathan, Emre Kultursay, Vinay Saripalli, Narayanan Vijaykrishnan, Mahmut T. Kandemir
ISLPED1
2011 Enabling architectural innovations using non-volatile memory
abstract
The emergence of non-volatile memory technologies such as Spin Torque Transfer Magneto-resistive Random Access Memory RAM and Phase Change Memories provide new opportunities for architectural innovations. While the zero off-state leakage, fast read access and high densities of these memories make them attractive options as compared to SRAM, their high write energies and latencies as well as their endurance are a concern. We provide three different architectural techniques that utilize the STT-MRAM characteristics to enable new functionalities. First, we show how exploiting the higher density of STT-MRAM in embedded multi-tasked systems can reduce the context switch overhead. Second, we use the STT-MRAM to create a reliable copy of SRAM structures vulnerable to radiation-induced transient errors to improve reliability. Finally, we show a hybrid cache architecture that uses a mix of emerging TFET technology and STT-MRAM technology. Our results indicate that active leakage is still a concern in STT-MRAM structures.
Narayanan Vijaykrishnan, Vinay Saripalli, Karthik Swaminathan, Ravindhiran Mukundrajan, Guangyu Sun 0003, Yuan Xie 0001, Suman Datta
ACM Great Lakes Symposium on VLSI3
2011 Improving energy efficiency of multi-threaded applications using heterogeneous CMOS-TFET multicores
Karthik Swaminathan, Emre Kultursay, Vinay Saripalli, Narayanan Vijaykrishnan, Mahmut T. Kandemir, Suman Datta
ISLPED1
2009 Performance optimizations for distributed real-time text indexing
abstract
DISC (Data-Intensive Super Computing) is gaining strong research momentum [1]. DISC systems differ from conventional supercomputers in their focus on data, as they acquire and maintain continually changing massive data sets, in addition to performing large-scale computations over the data. Towards this end, we consider the problem of real-time text indexing and search with high input data rates (10 GB/s or more) along with small index age-off time while sustaining search response time. Load imbalance and communication bottlenecks make this problem particularly challenging. We present performance optimizations for distributed in-memory text indexing of massive input data sets on parallel systems having large number of cores/processors, with sustained search performance [2]. Our distributed indexing algorithm uses a hybrid group-based approach which enables scalable indexing and search over massively parallel systems. In addition, we designed and analyzed communication optimizations including routing using Steiner nodes and topology mapping. Using theoretical analysis for the asymptotic parallel time complexity we establish the scalability of our algorithm with |P| for small index-group size and scalability with |C| for larger index-group size; where |P| and |C| are the number of Producers and Consumers respectively, in the index-group. We have obtained indexing throughput of 524 GB/min on 4K nodes of Blue Gene/L1using actual IBM intranet data, which is 3.36x better than the previous best throughput [3] and 10.3x better than typical indexing approaches such as CLucene2on the same number of nodes. This gives an estimated throughput of 17 TB/min on 128K nodes with sustained search performance. We also demonstrate the improvements in strong and weak scalability of our distributed indexing algorithm over the previous best [3] on Blue Gene/L. To the best of our knowledge, this is the highest indexing throughput ever published on a large scale system with sustained search performance.
Ankur Narang, Karthik Swaminathan, Prashant Agrawal
HiPC2