arXiv subjects

Jungrae Kim

Publications and source records attributed to Jungrae Kim.

5 recordsLinked to original sources

arXiv2026

Cerberus: Cross-Layer ECC Co-Design for Robust and Efficient Memory Protection

As DRAM scales to higher density and I/O speeds, ensuring data correctness becomes increasingly difficult. Industry has responded with a three-layer stack: on-die ECC (O-ECC), link ECC (L-ECC), and system ECC (S-ECC). However, these layers have evolved independently, often duplicating redundancy, leaving coverage gaps, and occasionally interfering. We propose Cerberus, a cross-layer ECC co-design that unifies protection across device, link, and system while preserving the native role of each layer. At its core is an Encode-Once, Decode-Many (EODM) architecture: the controller performs a single encoding whose redundancy is reused by L-ECC for immediate write-path detection and retry, by O-ECC for in-device repair on reads, and by S-ECC for strong end-to-end recovery. Cerberus jointly designs complementary parity and syndrome structures, orders decoders, and allocates the correction budget to prevent miscorrection amplification and enable selective correction under tight redundancy constraints. Our evaluations show improved resilience to clustered and peripheral faults while reducing redundant overhead, underscoring the importance of coordinated cross-layer protection for next-generation memory systems, such as custom HBMs.

cs.AR↗

arXiv2026

RangeGuard: Efficient, Bounded Approximate Error Correction for Reliable DNNs

As DRAM scales in density and adopts 3D integration, raw fault rates increase and multi-bit errors are no longer rare. Such errors can severely impact Deep Neural Networks (DNNs): although DNNs tolerate small numerical perturbations, random bit flips can create extreme outliers that propagate and sharply degrade accuracy. Large Language Models (LLMs) are particularly vulnerable because attention, residual, and normalization layers can amplify and preserve a single corrupted activation across many layers, destabilizing inference. This paper introduces RangeGuard, a metadata-centric error-correcting framework that provides strong reliability and high efficiency based on bounded approximate correction. Instead of protecting raw bits, RangeGuard encodes compact Range Identifiers (RIDs) that capture the numerical range of each value. These compact metadata enable efficient use of limited redundancy and concentrate protection on range changes, which indicate harmful semantic deviations, while ignoring benign intra-range variations. Upon detecting a range change, RangeGuard restores the correct range and substitutes a representative value, ensuring that error magnitudes are bounded within the range. Based on RIDs, RangeGuard can tolerate 64+ flipped bits using only 16 bits of parity available in GPU memories without a noticeable accuracy loss. By introducing semantic range protection, RangeGuard enables reliable DNN execution even under frequent memory errors and tight redundancy budgets.

cs.AR↗

arXiv2025

Modeling and Simulation Frameworks for Processing-in-Memory Architectures

Processing-in-Memory (PIM) has emerged as a promising computing paradigm to address the memory wall and the fundamental bottleneck of the von Neumann architecture by reducing costly data movement between memory and processing units. As with any engineering challenge, identifying the most effective solutions requires thorough exploration of diverse architectural proposals, device technologies, and application domains. In this context, simulation plays a critical role in enabling researchers to evaluate, compare, and refine PIM designs prior to fabrication. Over the past decade, a variety of PIM simulators have been introduced, spanning low-level device models, architectural frameworks, and application-oriented environments. These tools differ significantly in fidelity, scalability, supported memory/compute technologies, and benchmark compatibility. Understanding these trade-offs is essential for researchers to select appropriate simulators that accurately map and validate their research efforts. This chapter provides a comprehensive overview of PIM simulation methodologies and tools. We categorize simulators according to abstraction levels, design objectives, and evaluation metrics, highlighting representative examples. To improve accessibility, some content may appear in multiple contexts to guide readers with different backgrounds. We also survey benchmark suites commonly employed in PIM studies and discuss open challenges in simulation methodology, paving the way for more reliable, scalable, and efficient PIM modeling.

cs.AR↗

arXiv2025

Scaling Out Chip Interconnect Networks with Implicit Sequence Numbers

As AI models outpace the capabilities of single processors, interconnects across chips have become a critical enabler for scalable computing. These processors exchange massive amounts of data at cache-line granularity, prompting the adoption of new interconnect protocols like CXL, NVLink, and UALink, designed for high bandwidth and small payloads. However, the increasing transfer rates of these protocols heighten susceptibility to errors. While mechanisms like Cyclic Redundancy Check (CRC) and Forward Error Correction (FEC) are standard for reliable data transmission, scaling chip interconnects to multi-node configurations introduces new challenges, particularly in managing silently dropped flits in switching devices. This paper introduces Implicit Sequence Number (ISN), a novel mechanism that ensures precise flit drop detection and in-order delivery without adding header overhead. Additionally, we propose Reliability Extended Link (RXL), an extension of CXL that incorporates ISN to support scalable, reliable multi-node interconnects while maintaining compatibility with the existing flit structure. By elevating CRC to a transport-layer mechanism for end-to-end data and sequence integrity, and relying on FEC for link-layer error correction and detection, RXL delivers robust reliability and scalability without compromising bandwidth efficiency.

cs.NI↗

arXiv2024

Crumbled Cookie Exploring E-commerce Websites Cookie Policies with Data Protection Regulations

Despite stringent data protection regulations such as the General Data Protection Regulation (GDPR), the California Consumer Privacy Act (CCPA), and other country-specific regulations, many websites continue to use cookies to track user activities. Recent studies have revealed several data protection violations, resulting in significant penalties, especially for multinational corporations. Motivated by the question of why these data protection violations continue to occur despite strong data protection regulations, we examined 360 popular e-commerce websites in multiple countries to analyze whether they comply with regulations to protect user privacy from a cookie perspective.

cs.CY↗