Reddit ML report: same INT8 ONNX model showed major accuracy drift across Snapdragon tiers

What the community post reported

A technical discussion in r/MachineLearning presented a practical deployment warning for edge AI teams: identical model artifacts do not guarantee identical accuracy across mobile chipsets. The post reported testing one INT8-quantized ONNX model on five Snapdragon SoCs and listed a wide spread: 91.8% (8 Gen 3), 89.1% (8 Gen 2), 84.3% (7s Gen 2), 79.6% (6 Gen 1), and 71.2% (4 Gen 2). The same workflow also cited a 94.2% cloud benchmark for comparison.

Why this matters technically

The post attributes the drift to three implementation-level factors. First, different NPU generations can apply INT8 precision and rounding differently. Second, graph optimization and operator fusion in runtime stacks may vary by chipset profile, changing numerical behavior under the same exported model. Third, lower-tier devices may trigger memory-related fallbacks from NPU execution to CPU execution on some operators, effectively changing the inference path.

Even if each factor is expected in isolation, the combined effect is operationally significant: product decisions made on cloud benchmarks can miss failure modes that appear only on physical target devices.

Deployment implications for edge AI teams

The key lesson is not that INT8 is unreliable, but that validation strategy must be hardware-aware. Teams shipping mobile AI features should treat device matrix testing as a release gate, not a late QA task. Useful guardrails include per-chipset golden datasets, threshold-based regression alerts, runtime-level telemetry to detect fallback behavior, and policy-based model routing when low-end devices fail quality targets.

The thread reflects community-reported measurements rather than a peer-reviewed benchmark. Still, it captures a common blind spot in production ML ops: portability assumptions across heterogeneous accelerators are often too optimistic.

Sources: Reddit thread