arXiv subjects

Yuzhong Shen

Publications and source records attributed to Yuzhong Shen.

4 recordsLinked to original sources

arXiv2026

Validating LLM-Modernized Scientific Software Through Differential Fault Injection

Large language model (LLM) agents are increasingly used to modernize the legacy Fortran underlying production scientific software, but validation of these transformations emphasizes nominal executions and may not test whether a modernization preserves the original code's response to faults, perturbations, and reduced precision. We present a differential fault-injection validation method: a harness instruments the shared self-consistent-field driver of GAMESS at twelve sites and applies identical, deterministic faults to the original and LLM-modernized implementations, isolating the converted integral kernels. Across more than 2,200 runs, transient-fault absorption costs match a contraction-based model (predicted slopes 0.74 and 1.49 iterations per bit; measured 0.82 and 1.50), persistent perturbations halve final-energy error per additional bit, and the campaigns expose phase-dependent parallel deadlocks and false convergence under reduced precision. The original and modernized kernels agree in all 200 paired injections, and a measurement-guided synchronization change composes with the modernization, matching in all 40 pairs.

cs.DC↗

arXiv2026

An Agentic Workflow for Legacy HPC Modernization: Converting the Two-Electron-Integral Core of GAMESS

Modernizing legacy Fortran is a problem of volume: the transformations are individually routine, but the codebases can be enormous, and across much of computational science the work simply goes undone. We propose an agentic workflow that takes this work on at production scale, and we set out to measure how far such delegation can reach. In this work, three prompt-specialized agent roles operate under a version-controlled specification that the agents themselves authored and revised, while humans hold a small number of gates. The arrangement is kept safe by an exact verification oracle inherited from the domain, and the boundary of safe delegation lies exactly where that oracle stops seeing. We apply the proposed workflow in a case study, converting the two-electron-integral routines of GAMESS (General Atomic and Molecular Electronic Structure System), a mature quantum-chemistry package with a 48-year development history, from fixed-form Fortran 77 to free-form Fortran 2008. The scope of this work was twelve source files, 56,448 lines, and 225 subroutines for computing electron repulsion integrals. The agents ran as three Claude Code roles in isolated worktrees, and the work spanned four Claude model generations. Because the GAMESS group ships a standard test suite whose printed energies its user community treats as canonical, we could adopt bit-for-bit reproduction of those energies as the merge criterion, where a deviation in the twelfth decimal place counts as a failure rather than drift. All twelve source files pass a 51-test validation battery comprising the 49 standard GAMESS tests and two additional calculations, and across 612 test runs the number of chemistry-relevant differences is zero, and every file also passes the Jenkins tests that are used for continuous integration.

cs.AI↗

arXiv2015

Experimentation Procedure for Offloaded Mini-Apps Executed on Cluster Architectures with Xeon Phi Accelerators

A heterogeneous cluster architecture is complex. It contains hundreds, or thousands of devices connected by a tiered communication system in order to solve a problem. As a heterogeneous system, these devices will have varying performance capabilities. To better understand the interactions which occur between the various devices during execution, an experimentation procedure has been devised to capture, store, and analyze important and meaningful data. The procedure consists of various tools, techniques, and methods for capturing relevant timing, power, and performance data for a typical execution. This procedure currently applies to architectures with Intel Xeon processors and Intel Xeon Phi accelerators. It has been applied to the Co-Design Molecular Dynamics mini-app, courtesy of the ExMatEx team. This work aims to provide end-users with a strategy for investigating codes executed on heterogeneous cluster architectures with Xeon Phi accelerators.

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arXiv2015

Towards Modeling Energy Consumption of Xeon Phi

In the push for exascale computing, energy efficiency is of utmost concern. System architectures often adopt accelerators to hasten application execution at the cost of power. The Intel Xeon Phi co-processor is unique accelerator that offers application designers high degrees of parallelism, energy-efficient cores, and various execution modes. To explore the vast number of available configurations, a model must be developed to predict execution time, power, and energy for the CPU and Xeon Phi. An experimentation method has been developed which measures power for the CPU and Xeon Phi separately, as well as total system power. Execution time and performance are also captured for two experiments conducted in this work. The experiments, frequency scaling and strong scaling, will help validate the adopted model and assist in the development of a model which defines the host and Xeon Phi. The proxy applications investigated, representative of large-scale real-world applications, are Co-Design Molecular Dynamics (CoMD) and Livermore Unstructured Lagrangian Explicit Shock Hydrodynamics (LULESH). The frequency experiment discussed in this work is used to determine the time on-chip and off-chip to measure the compute- or latencyboundedness of the application. Energy savings were not obtained in symmetric mode for either application.

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