"SGLang enables the use of [LoRA adapters](https://arxiv.org/abs/2106.09685) with a base model. By incorporating techniques from [S-LoRA](https://arxiv.org/pdf/2311.03285) and [Punica](https://arxiv.org/pdf/2310.18547), SGLang can efficiently support multiple LoRA adapters for different sequences within a single batch of inputs."
]
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"source": [
"## Arguments for LoRA Serving"
]
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"The following server arguments are relevant for multi-LoRA serving:\n",
"\n",
"* `lora_paths`: A mapping from each adaptor's name to its path, in the form of `{name}={path} {name}={path}`.\n",
"\n",
"* `max_loras_per_batch`: Maximum number of adaptors used by each batch. This argument can affect the amount of GPU memory reserved for multi-LoRA serving, so it should be set to a smaller value when memory is scarce. Defaults to be 8.\n",
"\n",
"* `lora_backend`: The backend of running GEMM kernels for Lora modules. It can be one of `triton` or `flashinfer`, and set to `triton` by default. For better performance and stability, we recommend using the Triton LoRA backend. In the future, faster backend built upon Cutlass or Cuda kernels will be added.\n",
"* `max_lora_rank`: The maximum LoRA rank that should be supported. If not specified, it will be automatically inferred from the adapters provided in `--lora-paths`. This argument is needed when you expect to dynamically load adapters of larger LoRA rank after server startup.\n",
"\n",
"* `lora_target_modules`: The union set of all target modules where LoRA should be applied (e.g., `q_proj`, `k_proj`, `gate_proj`). If not specified, it will be automatically inferred from the adapters provided in `--lora-paths`. This argument is needed when you expect to dynamically load adapters of different target modules after server startup.\n",
"* `tp_size`: LoRA serving along with Tensor Parallelism is supported by SGLang. `tp_size` controls the number of GPUs for tensor parallelism. More details on the tensor sharding strategy can be found in [S-Lora](https://arxiv.org/pdf/2311.03285) paper.\n",
"\n",
"From client side, the user needs to provide a list of strings as input batch, and a list of adaptor names that each input sequence corresponds to."
"Instead of specifying all adapters during server startup via `--lora-paths`. You can also load & unload LoRA adapters dynamically via the `/load_lora_adapter` and `/unload_lora_adapter` API.\n",
"\n",
"(Please note that, currently we still require you to specify at least one adapter in `--lora-paths` to enable the LoRA feature, this limitation will be lifted soon.)"
"print(f\"Output from lora1: {response.json()[0]['text']}\")\n",
"print(f\"Output from lora2: {response.json()[1]['text']}\")"
]
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"terminate_process(server_process)"
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"source": [
"### Advanced: hosting adapters of different shapes\n",
"\n",
"In some cases, you may want to load LoRA adapters with different ranks or target modules (e.g., `q_proj`, `k_proj`) simultaneously. To ensure the server can accommodate all expected LoRA shapes, it's recommended to explicitly specify `--max-lora-rank` and/or `--lora-target-modules` at startup.\n",
"\n",
"For backward compatibility, SGLang will infer these values from `--lora-paths` if they are not explicitly provided. This means it's safe to omit them **only if** all dynamically loaded adapters share the same shape (rank and target modules) as those in the initial `--lora-paths` or are strictly \"smaller\"."
"# The `--target-lora-modules` param below is technically not needed, as the server will infer it from lora0 which already has all the target modules specified.\n",
"# We are adding it here just to demonstrate usage.\n",
"The development roadmap for LoRA-related features can be found in this [issue](https://github.com/sgl-project/sglang/issues/2929). Currently radix attention is incompatible with LoRA and must be manually disabled. Other features, including Unified Paging, Cutlass backend, and dynamic loading/unloadingm, are still under development."
