AI Inference: The Critical Layer Driving LLM Efficiency

AI Inference: The Critical Layer Driving LLM Efficiency

a16z Podcast Jan 22, 2026 english 5 min read

The AI industry's focus shifts from training smarter models to efficiently running them. Open-source solutions like VLLM are crucial for scaling LLM inference.

Key Insights

  • Insight

    The hardest problem in artificial intelligence has shifted from training smarter models to efficiently keeping them running, especially for large language models (LLMs).

    Impact

    This fundamental shift reorients research, development, and investment priorities towards robust and scalable AI infrastructure, crucial for the practical deployment and economic viability of advanced AI systems.

  • Insight

    LLM inference presents unique challenges due to dynamic request sizes, non-deterministic outputs, and asynchronous user demands, differing significantly from traditional static machine learning workloads.

    Impact

    Requires the development of specialized scheduling, memory management (e.g., page attention), and runtime optimizations to effectively utilize GPUs and handle the unpredictable nature of conversational AI.

  • Insight

    Open-source projects like VLLM are critical for building a universal inference layer that can support the diversity of AI models, hardware architectures, and applications.

    Impact

    Fosters a collaborative ecosystem, drives standardization, and enables faster innovation and broader adoption of AI across various industries by allowing all stakeholders to contribute and benefit.

  • Insight

    The increasing scale (multi-trillion parameters) and diversity (architecture, chip types) of AI models and deployment environments necessitate advanced distributed inference solutions and flexible runtimes.

    Impact

    Demands continuous innovation in sharding strategies, hardware-agnostic optimization, and model-specific adaptations to manage computational resources and ensure efficient performance for future AI systems.

  • Insight

    The emergence of AI agents with multi-turn conversations and external tool interactions introduces new complexities for inference, particularly in state management and cache eviction patterns.

    Impact

    Drives the need for co-optimized agent-inference architectures and more intelligent cache management mechanisms to support long-running, iterative AI processes with external dependencies.

  • Insight

    Inference engines are creating a fundamental horizontal abstraction layer for accelerated computing, akin to operating systems for CPUs or databases for storage devices.

    Impact

    This abstraction simplifies AI development and deployment by decoupling applications from underlying hardware complexities, making AI more accessible and efficient for a wider range of businesses and use cases.

Key Quotes

"I fundamentally believe that open source, especially how VLM itself is structured, is critical to the AI infrastructure in the world."
"What if the hardest problem in artificial intelligence isn't training smarter models, but simply keeping them running?"
"The goal of inference engine is to run the model at highly efficient speed to make sure that we can produce maximum output at the highest efficiency."

Summary

The Unseen Challenge: Mastering AI Inference

In the rapidly evolving landscape of artificial intelligence, a subtle yet profound shift is underway. While the headlines often trumpet breakthroughs in training smarter, more capable models, the industry's most pressing technical challenge is increasingly moving to the operational front: efficiently running these sophisticated AI systems, particularly Large Language Models (LLMs), at scale. This "hidden layer" of AI, known as inference, is now recognized as a critical bottleneck, demanding innovative solutions and a collaborative, open-source approach.

Why LLM Inference is a Unique Beast

Traditional machine learning workloads are often static and predictable, allowing for straightforward batch processing. LLMs, however, present a fundamentally different paradigm. Their auto-regressive nature means every request can be unique – from a single word prompt to an entire document – with outputs that are non-deterministic in length. This dynamism creates immense complexity for scheduling, memory management, and GPU utilization, hardware originally not designed for such chaotic, continuous demands. Technologies like "page attention" have emerged as foundational innovations to address these challenges, specifically in optimizing KV cache management for diverse and unpredictable conversational flows.

The Power of Open Source: VLLM and Its Ecosystem

At the heart of tackling these challenges is the open-source inference engine, VLLM. Born from a UC Berkeley research project, VLLM rapidly gained traction by offering a highly optimized runtime for LLMs. Its success is not just technical; it's a testament to the power of community-driven development. With thousands of contributors and active participation from major players across the AI stack – including model providers (like Meta, Red Hat), silicon manufacturers (NVIDIA, AMD, Google, Intel), and cloud infrastructure providers (AWS) – VLLM has become a crucial common standard. This collaborative model addresses the "M times M" problem, ensuring models run efficiently on diverse hardware, fostering innovation, and lowering deployment costs for everyone.

Scaling to the Future: Diversity, Distribution, and Agents

The challenges for inference are only escalating. Models are growing exponentially in scale, reaching multi-trillion parameters, necessitating complex sharding and distributed inference techniques across multiple GPUs and nodes. Simultaneously, there's an explosion in model diversity—from architecture variations (sparse vs. linear attention) to specialized models for vision, robotics, and language. The emergence of AI agents, engaging in multi-turn conversations and interacting with external tools, further complicates matters by introducing non-uniform cache access patterns and uncertain request return times. These trends demand a "universal inference layer" capable of adapting to continuous innovation in both model and hardware design.

Infract: Stewarding the Future of AI Infrastructure

Recognizing the profound importance of this foundational layer, the creators and maintainers of VLLM have launched Infract. The company's core mission is to support, maintain, and push forward the VLLM open-source ecosystem, aiming to establish VLLM as the world's inference engine. Infract envisions building a horizontal abstraction layer for accelerated computing, akin to operating systems for CPUs or databases for storage. This critical software layer will abstract away the complexities of GPUs and diverse models, making AI development and deployment more efficient, reliable, and accessible for all future generations of AI applications.

As AI continues its rapid advancement, the battle for efficiency and scalability in the inference layer will define the practical limits and economic viability of deploying these transformative technologies. Investing in and collaborating on open-source inference solutions is not merely a technical choice; it's a strategic imperative for any entity looking to leverage AI at the frontier.

Action Items

Prioritize investment and R&D in AI inference infrastructure, focusing on specialized engines and runtimes to address the operational challenges of LLMs.

Impact: This will lead to enhanced efficiency, reduced operational costs, and improved scalability and reliability of AI deployments, maximizing returns on AI model investments.

Actively contribute to and financially support open-source AI infrastructure projects like VLLM to accelerate the development of universal, adaptable AI systems.

Impact: Fosters a collaborative ecosystem, drives standardization, and provides access to cutting-edge technologies that benefit all participants across the AI value chain.

Develop and implement advanced scheduling and memory management strategies specifically designed to handle the dynamic and unpredictable nature of LLM inference requests.

Impact: Maximizes GPU utilization, reduces latency, and improves throughput for diverse real-world AI applications, delivering better user experiences and higher service capacity.

Design AI systems and infrastructure with foresight into the challenges posed by diverse model architectures, multi-chip deployments, and agentic workflows requiring persistent state management.

Impact: Ensures the future-proofing of AI investments and enables the seamless integration of advanced AI capabilities as the field evolves, avoiding costly architectural overhauls.

Foster deep collaboration between model developers, hardware manufacturers, and inference engine creators to co-optimize performance and ensure broad compatibility across the AI stack.

Impact: Creates a more harmonious and efficient AI ecosystem, reducing fragmentation, accelerating the adoption of new technologies, and unlocking greater overall system performance.

Mentioned Companies

Company created by VLLM founders to steward and push forward the open-source VLLM ecosystem, focusing on building a universal inference layer and supporting all AI workloads with extreme efficiency.

Mentioned as a general partner firm, providing grant funding to VLLM and investing in Infract, indicating strong support for the project and company's mission.

Discussed as a key hardware provider whose GPUs are being optimized by VLLM, with specific chips (H100, B200, GB200 MVL72) highlighted, underscoring its critical role in AI computing infrastructure.

Highlighted for running VLLM to power their Rufus assistant bot at massive scale, demonstrating real-world, large-scale adoption and impact of the inference engine in a critical consumer-facing application.

Highlighted as a first adopter of VLLM's cutting-edge features, rapidly rolling them out to hundreds of GPUs, demonstrating a strong reliance on the inference engine for advanced capabilities.

Mentioned for releasing the OPT model as open source and for contributing to the VLLM project, indicating its involvement in advancing open-source AI development.

Cited as an entity contributing to the VLLM open-source project, showcasing broad industry support and collaboration for the initiative.

Mentioned as a silicon provider participating in and supporting the VLLM ecosystem, implying its hardware compatibility and integration within the open-source framework.

Mentioned in the context of its TPU architecture and participation in the VLLM ecosystem, indicating its role in diverse AI hardware and open-source contributions.

Mentioned as having participation in and supporting the VLLM ecosystem, suggesting its role as a key infrastructure provider for AI deployments leveraging VLLM.

Mentioned as a silicon provider participating in and supporting the VLLM ecosystem, highlighting its contribution to hardware diversity in AI.

Listed as a major deployer of VLLM, indicating significant industry adoption of the inference engine for large-scale applications.

Mentioned as a company co-founded by Jan Stoika, who is also a co-advisor to the VLLM project and Infract, connecting the new venture to an established successful technology company.

Tags

Keywords

AI inference optimization LLM deployment challenges VLLM open source project AI infrastructure development distributed AI systems GPU efficiency for AI agentic AI infrastructure large language model scaling Infract AI company deep learning runtime