Asymmetric multiprocessing CPUs are central to mobile devices, but naive DNN scheduling across heterogeneous cores can degrade throughput because of workload imbalance. SANI combines an affinity-aware kernel issuer, an adaptive-granularity scheduler, and an on-demand kernel switcher to preserve core-kernel affinity while dynamically balancing work. Across five mobile SoCs, SANI reduces inference latency by 17.6%–23.7% on average, reaches up to 29.5% on individual models, and lowers energy consumption by up to 39% compared with state-of-the-art baselines.