Turn on flashinfer by default (#578)

README.md

@@ -34,6 +34,8 @@ The core features include:
 pip install "sglang[all]"
 ```
 
+Next, [install FlashInfer](https://docs.flashinfer.ai/installation.html) for attention CUDA kernels.
+
 ### Method 2: From source
 ```
 git clone https://github.com/sgl-project/sglang.git
@@ -43,7 +45,11 @@ pip install --upgrade pip
 pip install -e "python[all]"
 ```
 
+Next, [install FlashInfer](https://docs.flashinfer.ai/installation.html) for attention CUDA kernels.
+
 ### Notes
+- If you see triton errors, please install the [Triton Nightly](https://triton-lang.org/main/getting-started/installation.html).
+- If you cannot install FlashInfer, you can use the slower triton kernels by adding `--disable-flashinfer` when launching the server.
 - If you only need to use the OpenAI backend, you can avoid installing other dependencies by using `pip install "sglang[openai]"`
 
 ## Quick Start
@@ -363,7 +369,6 @@ python -m sglang.launch_server --model-path meta-llama/Llama-2-7b-chat-hf --port
 ```
 python -m sglang.launch_server --model-path meta-llama/Llama-2-7b-chat-hf --port 30000 --mem-fraction-static 0.7
 ```
-- See [flashinfer.md](docs/flashinfer.md) on accelerating inference using highly optimized CUDA kernels.
 - See [hyperparameter_tuning.md](docs/hyperparameter_tuning.md) on tuning hyperparameters for better performance.
 
 ### Supported Models

docs/flashinfer.md

-## Flashinfer Mode
-
-[flashinfer](https://github.com/flashinfer-ai/flashinfer) is a kernel library for LLM serving.
-It can be used in SGLang runtime to accelerate attention computation.
-
-### Install flashinfer
-
-See https://docs.flashinfer.ai/installation.html.
-
-### Run a Server With Flashinfer Mode
-
-Add `--enable-flashinfer` argument to enable flashinfer when launching a server.
-
-Example:
-
-```bash
-python -m sglang.launch_server --model-path meta-llama/Llama-2-7b-chat-hf --port 30000 --enable-flashinfer
-```

python/sglang/srt/layers/radix_attention.py

@@ -26,7 +26,7 @@ class RadixAttention(nn.Module):
 
         from sglang.srt.managers.controller.model_runner import global_server_args_dict
 
-        if global_server_args_dict.get("enable_flashinfer", False):
+        if not global_server_args_dict.get("disable_flashinfer", False):
             self.prefill_forward = self.prefill_forward_flashinfer
             self.extend_forward = self.prefill_forward_flashinfer
             self.decode_forward = self.decode_forward_flashinfer

python/sglang/srt/managers/controller/model_runner.py

@@ -201,7 +201,7 @@ class InputMetadata:
         if forward_mode == ForwardMode.EXTEND:
             ret.init_extend_args()
 
-        if global_server_args_dict.get("enable_flashinfer", False):
+        if not global_server_args_dict.get("disable_flashinfer", False):
             ret.init_flashinfer_args(
                 model_runner.model_config.num_attention_heads // tp_size,
                 model_runner.model_config.get_num_kv_heads(tp_size),
@@ -263,7 +263,7 @@ class ModelRunner:
         # Set some global args
         global global_server_args_dict
         global_server_args_dict = {
-            "enable_flashinfer": server_args.enable_flashinfer,
+            "disable_flashinfer": server_args.disable_flashinfer,
             "attention_reduce_in_fp32": server_args.attention_reduce_in_fp32,
         }
 
@@ -359,7 +359,7 @@ class ModelRunner:
         return c
 
     def init_flash_infer(self):
-        if global_server_args_dict.get("enable_flashinfer", False):
+        if not global_server_args_dict.get("disable_flashinfer", False):
             from flashinfer import (
                 BatchPrefillWithPagedKVCacheWrapper,
                 BatchDecodeWithPagedKVCacheWrapper,

python/sglang/srt/server_args.py

@@ -50,7 +50,7 @@ class ServerArgs:
     load_balance_method: str = "round_robin"
 
     # Optimization/debug options
-    enable_flashinfer: bool = False
+    disable_flashinfer: bool = True
     attention_reduce_in_fp32: bool = False
     disable_radix_cache: bool = False
     disable_regex_jump_forward: bool = False
@@ -287,9 +287,9 @@ class ServerArgs:
 
         # Optimization/debug options
         parser.add_argument(
-            "--enable-flashinfer",
+            "--disable-flashinfer",
             action="store_true",
-            help="Enable flashinfer inference kernels",
+            help="Disable flashinfer inference kernels",
         )
         parser.add_argument(
             "--attention-reduce-in-fp32",
@@ -322,7 +322,7 @@ class ServerArgs:
 
     def print_mode_args(self):
         return (
-            f"enable_flashinfer={self.enable_flashinfer}, "
+            f"disable_flashinfer={self.disable_flashinfer}, "
             f"attention_reduce_in_fp32={self.attention_reduce_in_fp32}, "
             f"disable_radix_cache={self.disable_radix_cache}, "
             f"disable_regex_jump_forward={self.disable_regex_jump_forward}, "