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llm.c ported to Mojo, runs 1.72x faster than PyTorch on Metal

Hacker News5h ago
llm.c ported to Mojo, runs 1.72x faster than PyTorch on Metal

Key takeaway

A developer has ported the llm.c inference framework to Mojo, a newer programming language, and achieved 1.72x faster performance than PyTorch when running on Metal (Apple's GPU framework). This shows Mojo can deliver meaningful performance gains for AI workloads on Apple hardware, which may interest developers building LLM applications for macOS and iOS.

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3 Key Points

  • What happened

    A developer ported llm.c (an LLM inference framework) to Mojo programming language with Metal GPU kernels, achieving 1.72x faster performance compared to PyTorch implementations on Metal hardware.

  • Why it matters

    This demonstrates that Mojo's language design and Metal kernel optimization can deliver significant speed improvements for AI workloads on Apple Silicon and compatible GPUs—relevant for developers looking to optimize LLM inference on macOS and iOS platforms.

  • What to watch

    The project is available on GitHub at ulmentflam/llm.mojo for developers interested in testing Mojo-based LLM inference or contributing further optimizations.

In Depth

The developer took llm.c, a minimalist C-based LLM inference framework designed for simplicity and efficiency, and reimplemented it in Mojo with custom Metal GPU kernels. The Mojo version achieved 1.72x faster performance compared to PyTorch implementations running on Metal hardware. The code is available on GitHub under the repository ulmentflam/llm.mojo for public use and further development. This effort highlights Mojo's potential to accelerate AI workloads on Apple's ecosystem, where Metal is the native GPU programming interface. For developers working with LLMs on macOS, iPad, or other Apple platforms, this result suggests Mojo could provide an alternative path to better performance without moving away from higher-level languages entirely.

Context & Analysis

This port represents a practical test of Mojo's claim to deliver high-performance AI code. Mojo is a newer programming language designed to bridge the gap between Python's ease of use and low-level performance optimization. By porting llm.c—a well-known lightweight LLM inference framework—to Mojo and pairing it with Metal kernels (Apple's GPU programming framework), the developer showed a concrete 1.72x speedup over PyTorch on the same hardware. This matters because PyTorch is the industry standard for ML development, and a substantial performance gap suggests Mojo could offer a meaningful alternative for developers targeting Apple Silicon devices, particularly in latency-sensitive applications like on-device inference.

FAQ

What performance improvement does the Mojo port deliver?
The Mojo implementation runs 1.72x faster than PyTorch implementations on Metal hardware.
Where can I find the code?
The project is available at https://github.com/ulmentflam/llm.mojo.

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