Files
project_6/upstream_ref/xllm/docs/zh/features/prefix_cache.md
EX Engine 002f9879b2 ref(upstream): FULL TREE — Deep-Spark xllm (1470) + ds_vllm csrc/models (703)
Replaces cherry-picked upstream_ref with complete source trees.

xllm/ — Iluvatar official C++ inference engine (15MB, 1470 files)
  Complete: kernels → layers → models → runtime → scheduler → api
  Excluded: .git, binary images, third_party submodule checkouts

ds_vllm/ — Iluvatar official vllm fork (8MB, 703 files)
  Included: csrc/ (ALL CUDA kernels), fused_moe/, qwen3_5 model, _custom_ops
  Excluded: tests, benchmarks, docs, examples (not needed for reference)

Critical call chains now fully traceable:
  MoE: moe_topk_softmax_kernels.cuh → ixformer.h → fused_moe.cpp → layer
  GDN: qwen3_gated_delta_net_base.cpp → qwen3_5_gated_delta_net.cpp
  Attention: ixformer.h → xllm_paged_attention → attention.cpp
2026-08-10 02:54:03 +00:00

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Prefix Cache 优化

功能介绍

xLLM支持prefix_cache匹配。prefix_cache基于mermer_hash使用lru淘汰策略提供更极致的匹配效率同时提高prefix_cache命中率。 同时对prefix_cache进行了优化支持continuous_scheduler、chunked_scheduler和zero_evict_scheduler在prefill之后即更新 prefix_cache提高匹配时效性同时对于chunked_scheduler支持多阶段chunked_prefill匹配减少计算量并尽可能减少kv_cache占用。

使用方式

prefix_cache已在xLLM实现并向外暴露gflag参数控制功能的开关。

  • 开启zero_evict策略并设置max_decode_token_per_sequence。
--enable_prefix_cache=true

性能效果

开启prefix_cache之后在Qwen3-8B模型上限制TPOT50msE2E时延 下降10%

!!! warning "注意" 暂不支持PD分离调度器