Files
sglang/benchmark/hicache
laoyao0822 7c8fa2f71c Remove full-cache scans from CP owner-lane allocation
The CP shared-KV allocator was still doing total-cache-sized CPU work in the scheduler hot path.  That cannot be hidden by GPU overlap, so owner-lane allocation now maintains per-owner free/release buckets and consumes request-sized prefixes instead of rebuilding masks over the full free-page tensor on each request.\n\nThe benchmark was extended to isolate L1 stats, selection, and allocation costs, and the CPU layout tests now install a complete sgl_kernel stub before importing SGLang helpers so remote unit collection does not abort in native extension loading.\n\nConstraint: Allocator CPU work blocks scheduler progress and cannot overlap with GPU forward execution.\nConstraint: CPU unit tests must not load native sgl_kernel on remote images where the loader can SIGABRT.\nRejected: Keep contiguous-run search over full free_pages | still scales with cache capacity and measured multi-ms overhead.\nRejected: Treat remote collection abort as an environment-only issue | it prevented allocator regression coverage and was fixable with a test-local stub.\nConfidence: high\nScope-risk: moderate\nDirective: CP owner-lane allocation is bucket-based; do not reintroduce full free_pages scans on the hot path without benchmark evidence.\nTested: Local py_compile for touched files\nTested: Local benchmark unit test, 6 passed\nTested: Remote benchmark unit test, 6 passed\nTested: Remote test_alloc_pages_with_owners.py, 10 passed\nTested: Remote test_cp_shared_kv_layout.py, 27 passed\nTested: Remote production allocator microbench shows select/alloc p50 reduced from ms-scale to sub-ms scale\nNot-tested: Full ETE traffic run after allocator bucket change
2026-06-02 08:41:00 +08:00
..

Run synthetic multi-turn benchmark

# SGLang server with radix cache disabled
python -m sglang.launch_server --model-path Qwen/Qwen2.5-14B-Instruct --port 30000 --disable-radix-cache

# SGLang server with radix cache on and first-come-first-serve policy
python -m sglang.launch_server --model-path Qwen/Qwen2.5-14B-Instruct --port 30000 --schedule-policy fcfs

# The default SGLang server with radix cache on and long-prefix-match policy
python -m sglang.launch_server --model-path Qwen/Qwen2.5-14B-Instruct --port 30000

# SGLang server with hierarchical radix cache enabled
python -m sglang.launch_server --model-path Qwen/Qwen2.5-14B-Instruct --port 30000 --enable-hierarchical-cache

python bench_multiturn.py --model-path Qwen/Qwen2.5-14B-Instruct

Note: The performance gain of hierarchical caching depends on the ratio of reusable tokens to GPU memory capacity. The more tokens to be reused, the larger the model, and the more constrained the GPU memory size, the greater the benefit one can expect from hierarchical caching.

Benchmark with more datasets

Download Dataset

./download.sh {sharegpt|ultragpt|loogle|nextqa|all}

This script will automatically download the required dataset to the current working directory

Multiturn Benchmark

Supported Datasets

  • sharegpt
  • ultrachat
  • loogle

Example Usage:

python3 bench_serving.py --model mistralai/Mistral-7B-Instruct-v0.3 --backend sglang \
--dataset-path longdep_qa.json --dataset-name loogle --request-rate 10 --num-prompts 10  \
--port 8001 --enable-multiturn --disable-shuffle

This uses mistralai/Mistral-7B-Instruct-v0.3 model with sglang as backend. The dataset is longdep_qa.json. We send 10 conversations with 10 req/s to port 8001. We enable multiturn chat without shuffling the order of conversations (i.e. following the original order in the dataset file).

Note:

The requests of multiple conversations are sent in a round robin fashion. For example, if we have 3 conversations A, B, C whose rounds are [2, 3, 4] correspondingly, multiturn chat will send the requests to the backend in the following order: [A1, B1, C1, A2, B2, C2, B3, C3, C4] This has implications on the cache reuse patterns: the cache reuse distance is the largest under this request pattern (which means a prefix-aware local scheduler in the backend can yield the most benefit compared to a FIFO scheduler)

Shared Prefix Benchmark

Supported Datasets

  • loogle

Example Usage:

python3 bench_serving.py --model mistralai/Mistral-7B-Instruct-v0.3 --backend sglang \
--dataset-path longdep_qa.json --dataset-name loogle --request-rate 10 --num-prompts 10  \
--port 8001 --enable-shared-prefix --disable-shuffle

Note:

Shared Prefix benchmark sends the questions for the same prompt together. For example, if we have 3 shared prefix A, B, C, which have [2, 3, 4] questions correspondingly, the shared prefix benchmark will send the requests to the backend in the following order: [A+Q1, A+Q2, B+Q1, B+Q2, B+Q3, C+Q1, C+Q2, C+Q3].

Multi Modality Benchmark (WIP)

Supported Datasets:

  • nextqa

Example Usage:

Server:
python3 -m sglang.launch_server --model-path lmms-lab/LLaVA-NeXT-Video-7B  --tp 2 --dp 1 --port 8001 \
--host 0.0.0.0 --mem-fraction-static 0.9 --tokenizer-path llava-hf/llava-1.5-7b-hf \
--json-model-override-args "{\"architectures\": [\"LlavaVidForCausalLM\"], \"model_type\":\"llava\", \"mm_spatial_pool_stride\":2}"

Client:
python3 bench_serving.py --model lmms-lab/LLaVA-NeXT-Video-7B --backend sglang  --dataset-path \
NExTVideo  --dataset-name nextqa --request-rate 10 --num-prompts 1 --disable-shuffle --port 8001 \ --enable-multiturn --max-frames 16 --tokenizer llava-hf/llava-1.5-7b-hf --fixed-output-len 2048

Note: for the server args, tokenizer-path, overriding architecture are necessary.

Supported Backend

  • sglang (oai)
  • vllm (oai)
  • lmdeploy (oai)