vLLM
An open-source LLM serving engine originally developed at UC Berkeley (Sky Computing Lab) that introduced **PagedAttention** — a paging-style KV-cache memory manager modeled on OS virtual memory. The block-based allocator eliminates KV-cache fragmentation, enables zero-copy prefix sharing across requests, and is now the reference implementation that most KV-cache-aware infrastructure (LMCache, Mooncake, NIXL, ObjectCache) targets.
Definition
An open-source LLM serving engine originally developed at UC Berkeley (Sky Computing Lab) that introduced **PagedAttention** — a paging-style KV-cache memory manager modeled on OS virtual memory. The block-based allocator eliminates KV-cache fragmentation, enables zero-copy prefix sharing across requests, and is now the reference implementation that most KV-cache-aware infrastructure (LMCache, Mooncake, NIXL, ObjectCache) targets.
Naive contiguous KV-cache allocation wastes 60-80% of GPU memory to internal fragmentation and pre-reserved padding. PagedAttention treats the KV-cache as fixed-size pages that can be allocated on demand, shared across requests with identical prefixes, swapped to CPU memory under pressure, and (with LMCache or ObjectCache) persisted to remote tiers. The result is multi-x throughput improvements at equivalent latency budgets.
Production LLM serving (text generation, chat completion, embedding), multi-tenant inference platforms (a single GPU pool serving many tenants with diverse prompt prefixes), prefix-cached agent workflows, RAG inference where the retrieved-context prefix is hot across requests.
Recent developments
AFD plugin — attention-FFN disaggregation for MoE serving (July 23). Splits attention and feed-forward computation onto separate workers so Mixture-of-Experts models can scale each phase independently; runs on both NVIDIA GPUs and Ascend NPUs — the second hardware ecosystem is a deliberate signal. Per the vLLM blog.
Production-scale Kimi K3 support with KDA-aware prefix caching + MXFP4 MoE (July 22). vLLM's prefix cache is now aware of Kimi's KDA attention structure, and MXFP4 quantization lands for MoE weights — frontier open-weight models get first-class serving the week they matter. Per the vLLM blog.
Semantic Router expands to Mixture-of-Models systems (July 21). The router that picked per-request paths inside one model family now routes across DIFFERENT models — vLLM positioning itself as the serving layer for heterogeneous model fleets, not single deployments. Per the vLLM blog.
Latest release: v0.30.0. vLLM ships rapidly; earlier references in this node reflect older minors (v0.27.1 was the current release as of August 2026). Per vLLM releases.
Native LMCache integration via the KVConnector interface. vLLM exposes a
KVConnectorinterface; LMCache plugs in as a remote-tier connector so prefix-cache lookups span GPU HBM → CPU DRAM → NVMe → S3-compatible object storage transparently. Per the vLLM repo and the LMCache repo.Prefill-decode disaggregation generally available. vLLM 0.10 split prefill-heavy (compute-bound) from decode-heavy (memory-bound) request scheduling into separate workers, enabling specialized GPU pools and reducing decode-stage tail latency. Per the vLLM repo.
Adopted as the kernel under Mooncake's serving plane. Moonshot's Mooncake project (the KV-cache-centric inference system behind Kimi) uses vLLM kernels internally with Mooncake's transfer engine replacing the prefix-cache store. Per Mooncake repo.
NIXL transfer-engine integration for RDMA prefix shipment. vLLM 0.10.5 added a NIXL-compatible transport so prefix-caches can be shipped between vLLM workers over RDMA (BlueField-4) at near-line-rate without staging through the host. Per the NVIDIA NIXL repo.
v1 engine core deadlocks under concurrent load when FP8 quantization, prefix caching, and Qwen3.5 architectures combine — tracked as issue #37729. Maintainers advise pinning to the older stable v0.6.14 release while avoiding v0.6.15, which carries its own autotuner regressions; teams running Qwen3.5 in FP8 with prefix caching enabled should hold at 0.6.14 rather than following the current release line until the deadlock is resolved. Per vllm-project/vllm issue #37729 (single-source GitHub issue, not yet corroborated by an official vLLM release note or blog post). Sources: vLLM project homepage · vLLM repo · LMCache repo · arXiv 2309.06180 — Efficient Memory Management for LLM Serving (the original PagedAttention paper, foundational reference)
0.28–0.29 attack cold-start and prefix reuse — but still not to object storage. Per vLLM releases, "Fast Start" adds a persistent per-GPU weight-cache daemon holding post-quantized, TP-sharded weights in GPU memory; a restarting engine maps them over CUDA IPC via
--load-format ipc_cache, skipping the reload from local disk or object storage entirely. Mamba prefix caching landed with a measured 9–25% TTFT improvement on internal prefill checkpoints.prefix_cache_retention_intervalbecame a CLI argument defaulting to 0, with dense retention restored automatically for hybrid EAGLE/MTP models, and Model Runner V2 is now the default for all models, adding CUDA-graph memory profiling for KV-cache auto-sizing and cutting per-step logits memory by a factor of the TP size. The honest negative, and it matters for this index: no KV-cache offload to an object-storage backend ships in these releases. The memory-tier work is real and stops at GPU/host memory — the S3 tier is still LMCache/Mooncake territory.
Connections20
Outbound9
integrates_with3enables1solves1alternative_to1competes_with1Inbound11
integrates_with4competes_with2