Callstack Dec 16, 2025

Profiling MLC-LLM's OpenCL Backend on Android: Performance Insights

Article Summary

Running LLMs on Android devices just got a serious performance deep-dive. Callstack profiled MLC-LLM's OpenCL backend to uncover what actually happens when you run local AI on mobile hardware.

This technical breakdown examines MLC-LLM's OpenCL backend performance on Android devices. The team at Callstack digs into the profiling data to understand bottlenecks, GPU utilization, and real-world performance characteristics of on-device inference.

Key Takeaways

Critical Insight

Understanding OpenCL backend performance is critical for shipping production-ready on-device AI features that actually perform well across Android's fragmented ecosystem.

The profiling data reveals some surprising insights about where mobile LLM inference actually spends its time.

About This Article

Problem

When running MLC-LLM's OpenCL backend on Android, the team needed to understand GPU utilization patterns and memory transfer bottlenecks. The fragmented hardware landscape made performance unpredictable across devices.

Solution

The team used profiling tools to capture detailed metrics on GPU compute operations, memory bandwidth usage, and CPU-GPU synchronization points. They ran these measurements during inference workloads on real Android devices.

Impact

The profiling data revealed specific performance characteristics for each device type. Developers can now optimize kernel execution and memory transfers based on these insights, which makes it possible to ship on-device AI that performs consistently across Android's diverse hardware.

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