This paper presents a bounded empirical study of runtime path observation and lane-control optimization on AMD Instinct MI25 (gfx900) under ROCm 7. 2. Rather than attempting to restore excluded modern paths, the study focuses on residual-path stabilization: identifying which computation paths remain reachable on MI25/gfx900, comparing reachable lanes under fixed anchor conditions, and maintaining explicit interpretation boundaries between catalog-read evidence, dispatch evidence, direct naming visibility, and kernel-level causality. Under fixed anchor conditions, changing exactly one runtime parameter (ROCBLASTENSILELIBPATH) produced an observed same-run throughput ratio of 8. 95x–9. 42x (3-run average: 9. 2476x). This is a condition-limited observation, not a universal MI25 performance claim. The paper contributes: a reusable observation workflow for layered GPU software stacks, an explicit evidence hierarchy to prevent overinterpretation, and a reproducible MI25/gfx900 case study under ROCm 7. 2. Keywords: ROCm, MI25, gfx900, AMD Instinct, lane comparison, observability, GPU software stack, runtime path analysis, Computing.
Akira Ito (Thu,) studied this question.