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[The Hidden Infrastructure of AI: Why Inference is the New Frontier]-[Inferact: Building the Infrastructure That Runs Modern AI]

a16z Podcast · B2 · 2026-01-22

Technology
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📋 Summary

The Hidden Infrastructure of AI: Why Inference is the New Frontier

As the public discourse surrounding Artificial Intelligence focuses heavily on training smarter models and achieving breakthrough performance, a critical and often overlooked challenge has emerged: inference. While training is the act of creation, inference—the process of running these models in real-time—has become the most complex and essential problem in modern computing. This shift is explored through the work of Simon Mo and Woosuk Kwon, co-founders of Infraact and lead contributors to the open-source inference engine vLLM.

The Shift from Static to Dynamic Workloads

Historically, computing systems were predictable. Once a program was written and executed, it operated within standardized parameters. Even early machine learning followed this pattern: inputs were regularized, and workloads were static. However, Large Language Models (LLMs) have fundamentally broken these assumptions.

As the podcast highlights, the dynamism of LLMs is inherent. Prompts can range from a single word to massive archives, and outputs can vary in length and duration. Unlike traditional image processing, where inputs are resized and compressed into static tensors, LLMs operate in a world of continuous, unpredictable, and stochastic flow. Consequently, the challenge has moved from simple execution to sophisticated scheduling and memory management.

The Birth and Evolution of vLLM

Woosuk Kwon explains that the vLLM project originated during his PhD at UC Berkeley in 2022, following Meta's release of the OPT model. What began as a side project to optimize a demo service quickly revealed that autoregressive transformers required a completely different approach to inference. The breakthrough, known as PagedAttention, was designed to address the unique memory management issues posed by these dynamic models.

What started as a research project rapidly evolved into a massive open-source ecosystem. Simon Mo emphasizes that vLLM has become a "universal inference layer," supported by over 2,000 contributors and deployed on hundreds of thousands of GPUs globally. The project has successfully solved the "M times M problem," providing a common ground where model providers, silicon vendors, and infrastructure operators can collaborate without needing to build custom solutions for every unique pairing of hardware and software.

The Three Pillars of Inference Complexity

According to the founders, the difficulty of running inference is increasing due to three primary factors:

  1. Scale: Models are ballooning toward multi-trillion parameters, requiring complex distributed systems to shard and run them across multiple nodes effectively.
  2. Diversity: The ecosystem is fracturing. With new architectures like sparse attention and linear attention emerging, and hardware varying from NVIDIA to TPU and custom chips, vLLM must continuously adapt to maintain efficiency across diverse environments.
  3. Agents: As AI systems transition from single-turn chatbots to agents that interact with external environments, the inference layer must manage state over long, iterative processes. Determining when a conversation is "finished" to clear the KV cache—a core component of transformer inference—has become a significant challenge in modern system design.

Open Source as a Strategic Imperative

Infraact’s philosophy is rooted in the belief that open-source infrastructure is critical to the future of AI. By building a universal inference layer, the company aims to move away from the "vertical slice" approach—where companies like OpenAI tightly control every aspect of their stack—toward a more modular, interoperable ecosystem.

Simon Mo notes that open source is their "secret weapon." Because the technology moves so rapidly, no single entity can keep up with the pace of innovation on their own. By fostering a community-driven model, they ensure that vLLM remains at the cutting edge, benefiting from contributions by companies like Amazon and Character AI, who rely on the engine for production-scale deployments.

Conclusion: The Future of the Inference Layer

Infraact’s mission is to steward this evolution. By treating inference as a foundational abstraction—much like operating systems or databases did for previous generations of computing—the team is building the runtime necessary for the next decade of AI. As the industry continues to push the boundaries of what is possible with accelerated computing, vLLM stands as the common infrastructure that enables diverse models to run with extreme efficiency, proving that in the world of AI, the infrastructure beneath the models may matter more than the models themselves.

🎯Key Sentences

1
Every request is different.
2
That's where the tension lies.
3
It is only that VLM win.
4
That was kind of at the beginning.
5
Actually, you're like doing more work instead of less.
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📝Key Phrases

1
push the capabilities
2
tailor that to extreme efficiency
3
in a sense
4
rival the challenge of
5
first-class citizen
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📖 Transcript

Our goal is to make VLM, the world's inference engine, really push the capabilities on the open source front and then build a universal inference layer.
That means we'll have the runtime to power any new model on new hardware for new application, be able to tailor that to extreme efficiency and support all the AI workload going forward.
I fundamentally believe that open source, especially how VLM itself is structured, is critical to the AI infrastructure in the world.
And what we want to do with Infraact is to support maintain, steward and push forward the open source ecosystem.
It is only that VLM win.
VLM becomes a standard and VLM help everybody to achieve what they need to do.

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