Topic

KV Cache Management

All digests tagged KV Cache Management

NVIDIA Dynamo in 5 Minutes: What Is It and Why Now? thumbnail

· 6:03

NVIDIA Dynamo in 5 Minutes: What Is It and Why Now?

NVIDIA Dynamo is a distributed serving layer designed to complement existing LLM inference engines (like SGLang, TensorRT-LLM, or vLLM). It addresses the complex challenges of scaling large language model inference across multi-GPU and multi-node clusters. Instead of being an inference engine itself, Dynamo coordinates workers, manages request routing, ensures fault tolerance, optimizes resource utilization through KV cache reuse, and provides a modular architecture for building complex production serving stacks.

Key takeaways

  1. Dynamo's Role in Scaling

    Dynamo acts as a distributed serving layer *around* inference engines. It coordinates the system to achieve multi-GPU and multi-node performance that single engines cannot provide alone. (0:32)

  2. Disaggregated Serving Efficiency 3:40

    It helps coordinate prefill (input prompt processing) and decode (token generation) phases across worker pools, which can have different resource needs, improving efficiency. (2:20)

  3. System Reliability and Scaling 5:05

    Dynamo provides crucial capabilities for production environments, including advanced request routing based on capacity/worker state, fault tolerance against node failures, and composability to connect various system components. (3:05)

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KV Cache-Aware Routing and P/D Disaggregation on Kubernetes — Yuchen Fama & Ashish Kamra, Red Hat thumbnail

· 21:48

KV Cache-Aware Routing and P/D Disaggregation on Kubernetes — Yuchen Fama & Ashish Kamra, Red Hat

This talk details advanced strategies for optimizing LLM inference in complex agentic workloads, moving beyond the limitations of steady-state public benchmarks. The focus is on two critical levers: KV Cache-Aware Routing and Prefill/Decode (P/D) Disaggregation. Implementing these techniques—using frameworks like LLMD—significantly improves latency and throughput by managing volatile cache usage and separating compute-bound prefill from memory-bandwidth-hungry decode phases, particularly in the middle concurrency band.

Key takeaways

  1. Agentic Workloads vs. Benchmarks 5:29

    Real-world agentic workloads exhibit chaotic multi-turn interactions (up to 3,000 turns) with high cache hit rates (>90%) and massive input/output ratios (often >100:1), which standard public benchmarks fail to capture [0:00], [3:29].

  2. KV Cache Routing Optimization 10:28

    Implementing KV cache-aware routing (via Endpoint Picker) is a cost-effective optimization, as the token cost difference between cached and uncached tokens can be as high as 10x [5:12]. This helps solve Time to First Token (TTFT) issues.

  3. P/D Disaggregation Benefits 15:28

    Separating prefill and decode into independent, scalable pods prevents 'phase interference'—where a long prefill stalls token generation (decode)—leading to drastically reduced P99 Inter Token Latency (ITL) from ~900ms down to ~100ms [9:28], [10:46].

  4. Prerequisites for PD 17:26

    Effective P/D disaggregation requires an advanced, high-speed network fabric like RDMA or RoCE to facilitate the transfer of KV caches between prefill and decode workers [10:46]. If such a fabric is unavailable, aggregated serving may be preferable.

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