Add Liquid Foundation Model (LFM2) (#16890)

This commit is contained in:
Piotr Mazurek
2026-01-22 04:11:20 +01:00
committed by GitHub
parent f2ae066a6b
commit d6e2b88288
11 changed files with 1493 additions and 7 deletions

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@@ -12,6 +12,7 @@ from sglang.srt.configs.jet_vlm import JetVLMConfig
from sglang.srt.configs.kimi_linear import KimiLinearConfig
from sglang.srt.configs.kimi_vl import KimiVLConfig
from sglang.srt.configs.kimi_vl_moonvit import MoonViTConfig
from sglang.srt.configs.lfm2 import Lfm2Config
from sglang.srt.configs.longcat_flash import LongcatFlashConfig
from sglang.srt.configs.nano_nemotron_vl import NemotronH_Nano_VL_V2_Config
from sglang.srt.configs.nemotron_h import NemotronHConfig
@@ -42,6 +43,7 @@ __all__ = [
"DotsVLMConfig",
"DotsOCRConfig",
"FalconH1Config",
"Lfm2Config",
"NemotronHConfig",
"NemotronH_Nano_VL_V2_Config",
"JetNemotronConfig",

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@@ -0,0 +1,102 @@
# coding=utf-8
# Copyright 2024 Liquid AI and the HuggingFace Inc. team. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""LFM2 (Liquid Foundation Model 2) configuration"""
from typing import List, Optional
from transformers import CONFIG_MAPPING
from transformers import Lfm2Config as HFLfm2Config
from transformers.utils import logging
from sglang.srt.configs.mamba_utils import Mamba2CacheParams, Mamba2StateShape
logger = logging.get_logger(__name__)
class Lfm2Config(HFLfm2Config):
"""
SGLang configuration for LFM2 models.
Extends HuggingFace's Lfm2Config with hybrid model properties needed by SGLang.
LFM2 uses a hybrid architecture mixing full attention and ShortConv layers.
"""
@property
def full_attention_layer_ids(self) -> List[int]:
"""Return indices of attention layers for KV cache."""
return [i for i, lt in enumerate(self.layer_types) if lt == "full_attention"]
@property
def linear_layer_ids(self) -> List[int]:
"""Return indices of conv layers for conv state cache."""
return [
i for i, lt in enumerate(self.layer_types) if lt in ("conv", "short_conv")
]
@property
def mamba_chunk_size(self) -> int:
"""Return chunk size for Mamba2 backend. LFM2 doesn't use chunking, return 1."""
return 1
@property
def mamba2_cache_params(self) -> Optional[Mamba2CacheParams]:
"""
Get cache params for HybridReqToTokenPool initialization.
LFM2 uses ShortConv layers with a small fixed-size cache (kernel_size - 1).
Unlike full Mamba2 models, LFM2 only uses the conv state, not SSM temporal state.
"""
from sglang.srt.layers.dp_attention import get_attention_tp_size
conv_layer_ids = self.linear_layer_ids
if not conv_layer_ids:
return None
hidden_size = self.hidden_size
# conv_L_cache in config is kernel_size (e.g., 3)
conv_kernel = int(self.conv_L_cache)
L_cache = conv_kernel - 1 # actual cache size (e.g., 2 for kernel=3)
# get_attention_tp_size() requires initialization, default to 1 if not available
try:
tp_size = get_attention_tp_size()
except (AssertionError, RuntimeError):
tp_size = 1
# For ShortConv layers, we use a simplified Mamba2StateShape
# LFM2 doesn't use SSM state (state_size=0), only conv state
shape = Mamba2StateShape.create(
tp_world_size=tp_size,
intermediate_size=hidden_size,
n_groups=1, # ShortConv doesn't use grouping
num_heads=1, # ShortConv is not multi-head
head_dim=hidden_size, # Conv operates on full hidden dim
state_size=0, # No SSM temporal state for ShortConv
conv_kernel=conv_kernel,
)
# Uses default mamba2_state_dtype() which reads SGLANG_MAMBA_CONV_DTYPE env var
# (defaults to bfloat16). Set SGLANG_MAMBA_CONV_DTYPE=float16 for fp16 inference.
return Mamba2CacheParams(
shape=shape,
layers=conv_layer_ids,
)
# Override HuggingFace's Lfm2Config with our extended version
# Cannot use .register() because lfm2 is already registered by transformers
# Directly modify the internal _extra_content dict instead
CONFIG_MAPPING._extra_content["lfm2"] = Lfm2Config
logger.info("Registered SGLang Lfm2Config to override HuggingFace's version")

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@@ -10,7 +10,7 @@
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Common config utils for mamba2 - NemotronH, FalconH1, Qwen3Next, etc."""
"""Common config utils for mamba2 - NemotronH, FalconH1, Qwen3Next, LFM2, etc."""
import os
from abc import ABC
@@ -41,16 +41,19 @@ class Mamba2StateDType:
temporal: torch.dtype
CONV_DTYPE = torch.bfloat16
def mamba2_state_dtype() -> Mamba2StateDType:
dtype_map = {
"float32": torch.float32,
"bfloat16": torch.bfloat16,
"float16": torch.float16,
}
ssm_dtype = dtype_map[os.environ["SGLANG_MAMBA_SSM_DTYPE"]]
return Mamba2StateDType(conv=CONV_DTYPE, temporal=ssm_dtype)
conv_dtype = dtype_map.get(
os.environ.get("SGLANG_MAMBA_CONV_DTYPE", "bfloat16"), torch.bfloat16
)
ssm_dtype = dtype_map.get(
os.environ.get("SGLANG_MAMBA_SSM_DTYPE", "float32"), torch.float32
)
return Mamba2StateDType(conv=conv_dtype, temporal=ssm_dtype)
@dataclass(kw_only=True, frozen=True)

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@@ -19,6 +19,7 @@ from sglang.srt.function_call.glm47_moe_detector import Glm47MoeDetector
from sglang.srt.function_call.gpt_oss_detector import GptOssDetector
from sglang.srt.function_call.internlm_detector import InternlmDetector
from sglang.srt.function_call.kimik2_detector import KimiK2Detector
from sglang.srt.function_call.lfm2_detector import Lfm2Detector
from sglang.srt.function_call.llama32_detector import Llama32Detector
from sglang.srt.function_call.mimo_detector import MiMoDetector
from sglang.srt.function_call.minimax_m2 import MinimaxM2Detector
@@ -51,6 +52,7 @@ class FunctionCallParser:
"glm47": Glm47MoeDetector,
"gpt-oss": GptOssDetector,
"kimi_k2": KimiK2Detector,
"lfm2": Lfm2Detector,
"llama3": Llama32Detector,
"mimo": MiMoDetector,
"mistral": MistralDetector,

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@@ -0,0 +1,387 @@
"""
Detector for LFM2 (Liquid Foundation Model 2) function call format.
Format Structure (Pythonic style):
```
<|tool_call_start|>[function_name(arg1="value1", arg2="value2")]<|tool_call_end|>
```
Multiple tool calls:
```
<|tool_call_start|>[func1(arg="val"), func2(arg="val")]<|tool_call_end|>
```
Also supports JSON format:
```
<|tool_call_start|>[{"name": "func_name", "arguments": {...}}]<|tool_call_end|>
```
"""
import ast
import json
import logging
import re
from typing import Any, Dict, List, Optional, Tuple
from sglang.srt.entrypoints.openai.protocol import Tool
from sglang.srt.environ import envs
from sglang.srt.function_call.base_format_detector import BaseFormatDetector
from sglang.srt.function_call.core_types import (
StreamingParseResult,
StructureInfo,
ToolCallItem,
_GetInfoFunc,
)
logger = logging.getLogger(__name__)
class Lfm2Detector(BaseFormatDetector):
"""
Detector for LFM2 (Liquid Foundation Model 2) function call format.
Supports both Pythonic and JSON formats:
Pythonic:
```
<|tool_call_start|>[calculator(expression="5 * 7")]<|tool_call_end|>
```
JSON:
```
<|tool_call_start|>[{"name": "calculator", "arguments": {"expression": "5 * 7"}}]<|tool_call_end|>
```
"""
def __init__(self):
"""
Initializes the detector with necessary state variables.
"""
super().__init__()
self.bot_token = "<|tool_call_start|>"
self.eot_token = "<|tool_call_end|>"
self.tool_call_separator = ""
def has_tool_call(self, text: str) -> bool:
"""Check if the text contains an LFM2 format tool call."""
return self.bot_token in text
def _get_parameter_value(self, val: ast.AST) -> Any:
"""
Extract Python literal value from AST node.
Handles constants, dicts, and lists recursively.
Reuses pattern from PythonicDetector.
"""
if isinstance(val, ast.Constant):
return val.value
elif isinstance(val, ast.Dict):
return {
self._get_parameter_value(k): self._get_parameter_value(v)
for k, v in zip(val.keys, val.values)
if k is not None # Handle {**kwargs} case where key is None
}
elif isinstance(val, ast.List):
return [self._get_parameter_value(v) for v in val.elts]
elif isinstance(val, ast.Tuple):
return tuple(self._get_parameter_value(v) for v in val.elts)
elif isinstance(val, ast.Name):
# Handle True, False, None as names in older Python
if val.id == "True":
return True
elif val.id == "False":
return False
elif val.id == "None":
return None
else:
raise ValueError(f"Unsupported name reference: {val.id}")
elif isinstance(val, ast.UnaryOp) and isinstance(val.op, ast.USub):
# Handle negative numbers like -5
inner = self._get_parameter_value(val.operand)
if isinstance(inner, (int, float)):
return -inner
raise ValueError(f"Cannot negate non-numeric value: {inner}")
else:
raise ValueError(
f"Tool call arguments must be literals, got: {type(val).__name__}"
)
def _parse_pythonic_call(
self, call: ast.Call, call_index: int, tool_indices: Dict[str, int]
) -> Optional[ToolCallItem]:
"""
Parse a single AST Call node into a ToolCallItem.
Args:
call: AST Call node representing a function call
call_index: Index of this call in the list of calls
tool_indices: Mapping of tool names to their indices
Returns:
ToolCallItem if successful, None if the call should be skipped
"""
if not isinstance(call.func, ast.Name):
logger.warning(
f"Tool call function must be a simple name, got: {type(call.func).__name__}"
)
return None
function_name = call.func.id
# Validate that the function exists in the tools
if function_name not in tool_indices:
logger.warning(
f"Model attempted to call undefined function: {function_name}"
)
if not envs.SGLANG_FORWARD_UNKNOWN_TOOLS.get():
return None # Skip unknown tools (default legacy behavior)
# Parse arguments
arguments = {}
for keyword in call.keywords:
if keyword.arg is None:
# **kwargs unpacking - skip for now
logger.warning("Tool call with **kwargs unpacking is not supported")
continue
try:
arguments[keyword.arg] = self._get_parameter_value(keyword.value)
except ValueError as e:
logger.warning(f"Failed to parse argument {keyword.arg}: {e}")
return None
return ToolCallItem(
tool_index=call_index, # Use the call index in the response, not tool position
name=function_name,
parameters=json.dumps(arguments, ensure_ascii=False),
)
def _parse_pythonic_content(
self, content: str, tools: List[Tool]
) -> Tuple[List[ToolCallItem], str]:
"""
Parse Pythonic format tool calls using AST.
Args:
content: The content between tool call tags (without the tags)
tools: List of available tools
Returns:
Tuple of (list of parsed calls, error message if any)
"""
content = content.strip()
tool_indices = self._get_tool_indices(tools)
try:
module = ast.parse(content)
parsed = getattr(module.body[0], "value", None) if module.body else None
if parsed is None:
return [], "Empty or invalid Python expression"
# Handle both single call and list of calls
if isinstance(parsed, ast.List):
call_nodes = parsed.elts
elif isinstance(parsed, ast.Call):
call_nodes = [parsed]
else:
return (
[],
f"Expected function call or list, got: {type(parsed).__name__}",
)
# Validate all elements are calls
if not all(isinstance(e, ast.Call) for e in call_nodes):
return [], "Not all elements in list are function calls"
calls = []
for call_index, call in enumerate(call_nodes):
item = self._parse_pythonic_call(call, call_index, tool_indices)
if item is not None:
calls.append(item)
return calls, ""
except SyntaxError as e:
return [], f"Python syntax error: {e}"
except Exception as e:
logger.exception("Unexpected error in pythonic tool call parsing")
return [], f"Unexpected error: {e}"
def _parse_json_content(
self, content: str, tools: List[Tool]
) -> Tuple[List[ToolCallItem], str]:
"""
Parse JSON format tool calls.
Uses parse_base_json from BaseFormatDetector for consistent handling
of SGLANG_FORWARD_UNKNOWN_TOOLS and tool validation.
Args:
content: The content between tool call tags (without the tags)
tools: List of available tools
Returns:
Tuple of (list of parsed calls, error message if any)
"""
content = content.strip()
try:
parsed = json.loads(content)
# parse_base_json handles list/dict normalization, tool validation,
# and SGLANG_FORWARD_UNKNOWN_TOOLS consistently with other detectors
calls = self.parse_base_json(parsed, tools)
return calls, ""
except json.JSONDecodeError as e:
return [], f"JSON parse error: {e}"
def _parse_tool_calls_content(
self, content: str, tools: List[Tool]
) -> List[ToolCallItem]:
"""
Parse the content between tool call tags.
Handles both JSON and Pythonic formats.
"""
content = content.strip()
# First, try JSON format (faster check)
if content.startswith("[{") or content.startswith("{"):
calls, error = self._parse_json_content(content, tools)
if calls:
return calls
# If JSON parsing failed but it looked like JSON, log the error
if error:
logger.debug(f"JSON parsing failed: {error}, trying Pythonic format")
# Try Pythonic format
calls, error = self._parse_pythonic_content(content, tools)
if calls:
return calls
if error:
logger.warning(f"Failed to parse tool calls: {error}")
return []
def detect_and_parse(self, text: str, tools: List[Tool]) -> StreamingParseResult:
"""
One-time parsing: Detects and parses tool calls in the provided text.
"""
idx = text.find(self.bot_token)
normal_text = text[:idx].strip() if idx != -1 else text
if self.bot_token not in text:
return StreamingParseResult(normal_text=normal_text, calls=[])
# Find all <|tool_call_start|>...<|tool_call_end|> blocks
pattern = rf"{re.escape(self.bot_token)}(.*?){re.escape(self.eot_token)}"
match_result_list = re.findall(pattern, text, re.DOTALL)
calls = []
for match_result in match_result_list:
parsed_calls = self._parse_tool_calls_content(match_result, tools)
calls.extend(parsed_calls)
return StreamingParseResult(normal_text=normal_text, calls=calls)
def _strip_special_tokens(self, text: str) -> str:
"""Remove special tokens from text."""
return text.replace(self.bot_token, "").replace(self.eot_token, "")
def parse_streaming_increment(
self, new_text: str, tools: List[Tool]
) -> StreamingParseResult:
"""
Streaming incremental parsing for LFM2 tool calls.
This implementation properly handles Pythonic format by:
1. Buffering until we see complete <|tool_call_start|>[...]<|tool_call_end|>
2. Emitting normal text before tool calls immediately
3. Parsing complete tool call blocks using detect_and_parse
Based on PythonicDetector streaming logic.
"""
self._buffer += new_text
# Check for partial bot_token at the end
partial_bot = self._ends_with_partial_token(self._buffer, self.bot_token)
partial_eot = self._ends_with_partial_token(self._buffer, self.eot_token)
# Find bot_token position
bot_pos = self._buffer.find(self.bot_token)
if bot_pos == -1:
# No tool call start found
if partial_bot:
# Might be partial bot_token, hold back that part
safe_text = self._buffer[:-partial_bot]
self._buffer = self._buffer[-partial_bot:]
return StreamingParseResult(normal_text=safe_text)
else:
# No tool call, emit all as normal text
normal_text = self._strip_special_tokens(self._buffer)
self._buffer = ""
return StreamingParseResult(normal_text=normal_text)
# We have bot_token - extract any normal text before it
normal_text_before = self._buffer[:bot_pos] if bot_pos > 0 else ""
# Look for the end token
eot_pos = self._buffer.find(self.eot_token, bot_pos + len(self.bot_token))
if eot_pos == -1:
# No end token yet - check if we might have a partial one
if partial_eot:
# Hold back the partial token, but we need to keep buffering
# Just emit any normal text before the tool call
if normal_text_before:
self._buffer = self._buffer[bot_pos:]
return StreamingParseResult(normal_text=normal_text_before)
# Keep buffering
return StreamingParseResult(normal_text="")
# No end token and no partial - keep buffering but emit normal text
if normal_text_before:
self._buffer = self._buffer[bot_pos:]
return StreamingParseResult(normal_text=normal_text_before)
# Just keep buffering
return StreamingParseResult(normal_text="")
# We have a complete tool call block
tool_call_block = self._buffer[bot_pos : eot_pos + len(self.eot_token)]
remaining = self._buffer[eot_pos + len(self.eot_token) :]
# Parse the complete block
result = self.detect_and_parse(tool_call_block, tools)
# Update buffer with remaining text
self._buffer = remaining
# Add any normal text before the tool call
if normal_text_before:
result.normal_text = normal_text_before + (result.normal_text or "")
return result
def supports_structural_tag(self) -> bool:
"""
Return False because LFM2 uses Pythonic format which is not JSON-compatible.
structural_tag only supports JSON-compatible content between begin and end,
so it cannot parse Pythonic function call syntax like `func(arg="val")`.
"""
return False
def structure_info(self) -> _GetInfoFunc:
"""
Return structure info for constrained generation.
Note: This is provided for completeness but won't be used since
supports_structural_tag() returns False.
"""
return lambda name: StructureInfo(
begin="<|tool_call_start|>[" + name + "(",
end=")]<|tool_call_end|>",
trigger="<|tool_call_start|>",
)

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@@ -35,6 +35,7 @@ from sglang.srt.configs import (
JetNemotronConfig,
JetVLMConfig,
KimiLinearConfig,
Lfm2Config,
NemotronH_Nano_VL_V2_Config,
NemotronHConfig,
Qwen3NextConfig,
@@ -1491,7 +1492,7 @@ class ModelRunner(ModelRunnerKVCacheMixin):
pattern = getattr(config, "mtp_hybrid_override_pattern", None)
if pattern is not None and "M" not in pattern:
return None
if isinstance(config, FalconH1Config | NemotronHConfig):
if isinstance(config, FalconH1Config | NemotronHConfig | Lfm2Config):
return config
if isinstance(config, NemotronH_Nano_VL_V2_Config):
return config.llm_config

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@@ -0,0 +1,566 @@
"""
LFM2 (Liquid Foundation Model 2) implementation for SGLang.
This is a hybrid architecture with both attention and short conv layers.
- Attention layers use standard KV cache (RadixAttention)
- Conv layers use MambaPool for state caching (via HybridReqToTokenPool)
The model uses a gated 1D causal convolution (kernel=3) instead of attention
in some layers, providing linear memory complexity for those layers.
Uses optimized causal_conv1d kernels from the mamba package for fast inference.
"""
import logging
from typing import Iterable, Optional, Set, Tuple
import torch
import torch.nn.functional as F
from torch import nn
from sglang.srt.configs.lfm2 import Lfm2Config
from sglang.srt.distributed import get_pp_group
from sglang.srt.layers.attention.mamba.causal_conv1d import (
causal_conv1d_fn,
causal_conv1d_update,
)
from sglang.srt.layers.layernorm import RMSNorm
from sglang.srt.layers.linear import (
ColumnParallelLinear,
QKVParallelLinear,
RowParallelLinear,
)
from sglang.srt.layers.logits_processor import LogitsProcessor
from sglang.srt.layers.quantization.base_config import QuantizationConfig
from sglang.srt.layers.radix_attention import RadixAttention
from sglang.srt.layers.rotary_embedding import get_rope
from sglang.srt.layers.vocab_parallel_embedding import (
ParallelLMHead,
VocabParallelEmbedding,
)
from sglang.srt.model_executor.forward_batch_info import ForwardBatch
from sglang.srt.model_loader.weight_utils import default_weight_loader
from sglang.srt.utils import add_prefix, make_layers
logger = logging.getLogger(__name__)
# We don't use it, we keep it for reference. If we run sglang.srt.layers.layernorm.RMSNorm
# kernel the difference in logprobs slightly increases, but to an acceptable degree
# class Lfm2RMSNorm(nn.Module):
# """LFM2-specific RMSNorm: weight * x (not (1 + weight) * x like Gemma)."""
# def __init__(self, hidden_size: int, eps: float = 1e-6):
# super().__init__()
# self.weight = nn.Parameter(torch.ones(hidden_size))
# self.variance_epsilon = eps
# def forward(self, hidden_states: torch.Tensor) -> torch.Tensor:
# input_dtype = hidden_states.dtype
# hidden_states = hidden_states.to(torch.float32)
# variance = hidden_states.pow(2).mean(-1, keepdim=True)
# hidden_states = hidden_states * torch.rsqrt(variance + self.variance_epsilon)
# return (self.weight * hidden_states).to(input_dtype)
class Lfm2MLP(nn.Module):
"""MLP with SwiGLU activation."""
def __init__(
self,
config: Lfm2Config,
quant_config: Optional[QuantizationConfig] = None,
prefix: str = "",
):
super().__init__()
intermediate_size = config.intermediate_size
if config.block_auto_adjust_ff_dim:
intermediate_size = int(2 * intermediate_size / 3)
if config.block_ffn_dim_multiplier is not None:
intermediate_size = int(
config.block_ffn_dim_multiplier * intermediate_size
)
intermediate_size = config.block_multiple_of * (
(intermediate_size + config.block_multiple_of - 1)
// config.block_multiple_of
)
self.w1 = ColumnParallelLinear(
config.hidden_size,
intermediate_size,
bias=False,
quant_config=quant_config,
prefix=add_prefix("w1", prefix),
)
self.w3 = ColumnParallelLinear(
config.hidden_size,
intermediate_size,
bias=False,
quant_config=quant_config,
prefix=add_prefix("w3", prefix),
)
self.w2 = RowParallelLinear(
intermediate_size,
config.hidden_size,
bias=False,
quant_config=quant_config,
prefix=add_prefix("w2", prefix),
)
def forward(self, x: torch.Tensor) -> torch.Tensor:
gate, _ = self.w1(x)
up, _ = self.w3(x)
out, _ = self.w2(F.silu(gate) * up)
return out
class Lfm2Attention(nn.Module):
"""Grouped-query attention with RoPE and Q/K layernorm."""
def __init__(
self,
config: Lfm2Config,
layer_id: int,
attn_layer_id: int,
quant_config: Optional[QuantizationConfig] = None,
prefix: str = "",
) -> None:
super().__init__()
self.hidden_size = config.hidden_size
self.total_num_heads = config.num_attention_heads
self.total_num_kv_heads = config.num_key_value_heads
self.head_dim = getattr(config, "head_dim", None) or (
self.hidden_size // self.total_num_heads
)
self.scaling = self.head_dim**-0.5
rope_parameters = getattr(config, "rope_parameters", None)
if rope_parameters is not None and "rope_theta" in rope_parameters:
rope_theta = rope_parameters["rope_theta"]
else:
rope_theta = getattr(config, "rope_theta", 10000)
self.rotary_emb = get_rope(
head_size=self.head_dim,
rotary_dim=self.head_dim,
max_position=getattr(config, "max_position_embeddings", 8192),
rope_scaling=getattr(config, "rope_scaling", None),
base=rope_theta,
is_neox_style=True,
dtype=torch.get_default_dtype(),
)
self.qkv_proj = QKVParallelLinear(
self.hidden_size,
self.head_dim,
self.total_num_heads,
self.total_num_kv_heads,
bias=False,
quant_config=quant_config,
prefix=add_prefix("qkv_proj", prefix),
)
self.out_proj = RowParallelLinear(
self.total_num_heads * self.head_dim,
self.hidden_size,
bias=False,
quant_config=quant_config,
prefix=add_prefix("out_proj", prefix),
)
self.q_layernorm = RMSNorm(self.head_dim, eps=config.norm_eps)
self.k_layernorm = RMSNorm(self.head_dim, eps=config.norm_eps)
self.num_local_q_heads = self.qkv_proj.num_heads
self.num_local_kv_heads = self.qkv_proj.num_kv_heads
self.attn = RadixAttention(
num_heads=self.num_local_q_heads,
head_dim=self.head_dim,
scaling=self.scaling,
num_kv_heads=self.num_local_kv_heads,
layer_id=layer_id,
prefix=add_prefix("attn", prefix),
)
def forward(
self,
positions: torch.Tensor,
hidden_states: torch.Tensor,
forward_batch: ForwardBatch,
) -> torch.Tensor:
T = hidden_states.shape[0]
qkv, _ = self.qkv_proj(hidden_states)
q_size = self.num_local_q_heads * self.head_dim
kv_size = self.num_local_kv_heads * self.head_dim
q, k, v = torch.split(qkv, [q_size, kv_size, kv_size], dim=-1)
q = q.reshape(T, self.num_local_q_heads, self.head_dim)
k = k.reshape(T, self.num_local_kv_heads, self.head_dim)
q = self.q_layernorm(q.reshape(-1, self.head_dim)).reshape(
T, self.num_local_q_heads, self.head_dim
)
k = self.k_layernorm(k.reshape(-1, self.head_dim)).reshape(
T, self.num_local_kv_heads, self.head_dim
)
q, k = self.rotary_emb(positions, q, k)
attn_out = self.attn(q.reshape(T, -1), k.reshape(T, -1), v, forward_batch)
out, _ = self.out_proj(attn_out)
return out
class Lfm2ShortConv(nn.Module):
"""
Gated short convolution layer using optimized causal_conv1d kernels.
Architecture: in_proj -> split(B, C, x) -> Bx -> conv1d -> C*conv_out -> out_proj
- Uses double gating: B (before conv) and C (after conv)
- Fixed-size cache: stores last (kernel_size - 1) tokens
- Uses causal_conv1d_fn for prefill and causal_conv1d_update for decode
"""
def __init__(
self,
config: Lfm2Config,
layer_idx: int,
quant_config: Optional[QuantizationConfig] = None,
prefix: str = "",
):
super().__init__()
self.layer_idx = layer_idx
self.conv_kernel = int(config.conv_L_cache)
self.L_cache = self.conv_kernel - 1
self.use_bias = bool(config.conv_bias)
self.hidden_size = config.hidden_size
self.in_proj = nn.Linear(
config.hidden_size, 3 * config.hidden_size, bias=self.use_bias
)
self.out_proj = nn.Linear(
config.hidden_size, config.hidden_size, bias=self.use_bias
)
# Conv weights stored in format matching causal_conv1d: (hidden_size, kernel_size)
# Weight loading will handle conversion from HF's (hidden_size, 1, kernel_size)
self.conv_weight = nn.Parameter(
torch.empty(config.hidden_size, self.conv_kernel)
)
if self.use_bias:
self.conv_bias = nn.Parameter(torch.empty(config.hidden_size))
else:
self.register_parameter("conv_bias", None)
def forward(
self,
hidden_states: torch.Tensor,
forward_batch: ForwardBatch,
) -> torch.Tensor:
if forward_batch.forward_mode.is_idle():
return hidden_states
layer_cache = forward_batch.req_to_token_pool.mamba2_layer_cache(self.layer_idx)
conv_state = layer_cache.conv[0]
req_pool_indices = forward_batch.req_pool_indices
# Project and split into gates: B (pre-conv), C (post-conv), x (input)
proj = self.in_proj(hidden_states)
B_gate, C_gate, x = proj.chunk(3, dim=-1)
Bx = B_gate * x
if forward_batch.forward_mode.is_decode():
# Decode: single token per request, use optimized update kernel
conv_out = causal_conv1d_update(
Bx,
conv_state,
self.conv_weight,
self.conv_bias,
activation=None,
conv_state_indices=req_pool_indices.to(torch.int32),
)
else:
# Prefill: multiple tokens, use varlen kernel
T = hidden_states.shape[0]
Bx_t = Bx.transpose(0, 1).contiguous()
# Build query_start_loc: [0, cumsum(seq_lens)...]
extend_start_loc = forward_batch.extend_start_loc
if extend_start_loc is not None and len(extend_start_loc) > 1:
query_start_loc = torch.cat(
[
extend_start_loc,
torch.tensor(
[T], dtype=torch.int32, device=hidden_states.device
),
]
)
cache_indices = req_pool_indices.to(torch.int32)
else:
query_start_loc = torch.tensor(
[0, T], dtype=torch.int32, device=hidden_states.device
)
cache_indices = req_pool_indices[:1].to(torch.int32)
conv_out = causal_conv1d_fn(
Bx_t,
self.conv_weight,
self.conv_bias,
query_start_loc=query_start_loc,
cache_indices=cache_indices,
has_initial_state=None,
conv_states=conv_state,
activation=None,
).transpose(0, 1)
return self.out_proj(C_gate * conv_out)
class Lfm2DecoderLayer(nn.Module):
"""Decoder layer - either attention or conv based on config."""
def __init__(
self,
config: Lfm2Config,
layer_id: int,
attn_layer_id: int,
quant_config: Optional[QuantizationConfig] = None,
prefix: str = "",
):
super().__init__()
self.layer_type = config.layer_types[layer_id]
self.is_attention_layer = self.layer_type == "full_attention"
self.operator_norm = RMSNorm(config.hidden_size, eps=config.norm_eps)
self.ffn_norm = RMSNorm(config.hidden_size, eps=config.norm_eps)
if self.is_attention_layer:
self.self_attn = Lfm2Attention(
config=config,
layer_id=layer_id,
attn_layer_id=attn_layer_id,
quant_config=quant_config,
prefix=add_prefix("self_attn", prefix),
)
else:
self.conv = Lfm2ShortConv(
config=config,
layer_idx=layer_id,
quant_config=quant_config,
prefix=add_prefix("conv", prefix),
)
self.feed_forward = Lfm2MLP(
config=config,
quant_config=quant_config,
prefix=add_prefix("feed_forward", prefix),
)
def forward(
self,
layer_id: int,
positions: torch.Tensor,
hidden_states: torch.Tensor,
residual: Optional[torch.Tensor],
forward_batch: ForwardBatch,
**kwargs,
) -> Tuple[torch.Tensor, torch.Tensor]:
if not forward_batch.forward_mode.is_idle():
residual = hidden_states
normed = self.operator_norm(hidden_states)
if self.is_attention_layer:
hidden_states = self.self_attn(positions, normed, forward_batch)
else:
hidden_states = self.conv(normed, forward_batch)
hidden_states = hidden_states + residual
hidden_states = hidden_states + self.feed_forward(
self.ffn_norm(hidden_states)
)
return hidden_states, residual
class Lfm2Model(nn.Module):
def __init__(
self,
config: Lfm2Config,
quant_config: Optional[QuantizationConfig] = None,
prefix: str = "",
):
super().__init__()
self.config = config
self.embed_tokens = VocabParallelEmbedding(
config.vocab_size,
config.hidden_size,
org_num_embeddings=config.vocab_size,
prefix=add_prefix("embed_tokens", prefix),
)
# Compute attention layer IDs for KV cache
attn_layer_ids = []
attn_count = 0
for layer_type in config.layer_types:
if layer_type == "full_attention":
attn_layer_ids.append(attn_count)
attn_count += 1
else:
attn_layer_ids.append(-1)
self.num_attention_layers = attn_count
def get_layer(idx: int, prefix: str, **kwargs):
return Lfm2DecoderLayer(
config=config,
layer_id=idx,
attn_layer_id=attn_layer_ids[idx],
quant_config=quant_config,
prefix=prefix,
)
self.layers = make_layers(
config.num_hidden_layers, get_layer, prefix=f"{prefix}.layers"
)
self.embedding_norm = RMSNorm(config.hidden_size, eps=config.norm_eps)
def forward(
self,
input_ids: torch.Tensor,
positions: torch.Tensor,
forward_batch: ForwardBatch,
inputs_embeds: Optional[torch.Tensor] = None,
) -> torch.Tensor:
hidden_states = (
inputs_embeds if inputs_embeds is not None else self.embed_tokens(input_ids)
)
residual = None
for i in range(len(self.layers)):
hidden_states, residual = self.layers[i](
layer_id=i,
positions=positions,
hidden_states=hidden_states,
residual=residual,
forward_batch=forward_batch,
)
return self.embedding_norm(hidden_states)
class Lfm2ForCausalLM(nn.Module):
"""LFM2 for causal language modeling with hybrid attention/conv architecture."""
fall_back_to_pt_during_load = False
def __init__(
self,
config: Lfm2Config,
quant_config: Optional[QuantizationConfig] = None,
prefix: str = "",
) -> None:
super().__init__()
self.config = config
self.pp_group = get_pp_group()
assert self.pp_group.is_first_rank and self.pp_group.is_last_rank
self.quant_config = quant_config
self.model = Lfm2Model(config, quant_config, prefix=add_prefix("model", prefix))
self.lm_head = ParallelLMHead(
config.vocab_size,
config.hidden_size,
quant_config=quant_config,
org_num_embeddings=config.vocab_size,
prefix=add_prefix("lm_head", prefix),
)
self.logits_processor = LogitsProcessor(config)
self.num_attention_layers = self.model.num_attention_layers
def get_num_kv_cache_layers(self) -> int:
return self.num_attention_layers
@torch.no_grad()
def forward(
self,
input_ids: torch.Tensor,
positions: torch.Tensor,
forward_batch: ForwardBatch,
inputs_embeds: Optional[torch.Tensor] = None,
**kwargs,
):
hidden_states = self.model(input_ids, positions, forward_batch, inputs_embeds)
return self.logits_processor(
input_ids, hidden_states, self.lm_head, forward_batch
)
def load_weights(
self, weights: Iterable[Tuple[str, torch.Tensor]], is_mtp: bool = False
) -> Set[str]:
stacked_params_mapping = [
("qkv_proj", "q_proj", "q"),
("qkv_proj", "k_proj", "k"),
("qkv_proj", "v_proj", "v"),
]
params_dict = dict(self.named_parameters())
loaded_params: Set[str] = set()
embed_tokens_weight = None
for name, loaded_weight in weights:
if "rotary_emb.inv_freq" in name:
continue
if "embed_tokens.weight" in name:
embed_tokens_weight = loaded_weight
# Handle conv.weight -> conv_weight conversion for ShortConv layers
# HF shape: (hidden_size, 1, kernel_size) -> squeeze to (hidden_size, kernel_size)
if ".conv.weight" in name:
name = name.replace(".conv.weight", ".conv_weight")
# Squeeze out the middle dimension: (D, 1, K) -> (D, K)
loaded_weight = loaded_weight.squeeze(1)
# Handle conv.bias -> conv_bias conversion
if ".conv.bias" in name:
name = name.replace(".conv.bias", ".conv_bias")
# Handle QKV stacking
for param_name, weight_name, shard_id in stacked_params_mapping:
if weight_name not in name:
continue
name = name.replace(weight_name, param_name)
if name.endswith(".bias") and name not in params_dict:
break
if name not in params_dict:
break
param = params_dict[name]
weight_loader = getattr(param, "weight_loader")
weight_loader(param, loaded_weight, shard_id)
loaded_params.add(name)
break
else:
if name.endswith(".bias") and name not in params_dict:
continue
if name not in params_dict:
continue
param = params_dict[name]
weight_loader = getattr(param, "weight_loader", default_weight_loader)
weight_loader(param, loaded_weight)
loaded_params.add(name)
# Handle tied lm_head weight
if "lm_head.weight" not in loaded_params and "lm_head.weight" in params_dict:
if embed_tokens_weight is not None:
param = params_dict["lm_head.weight"]
weight_loader = getattr(param, "weight_loader", default_weight_loader)
weight_loader(param, embed_tokens_weight)
loaded_params.add("lm_head.weight")
return loaded_params
EntryClass = [Lfm2ForCausalLM]

View File

@@ -1592,6 +1592,33 @@ class ServerArgs:
)
self.disable_radix_cache = True
self.disable_overlap_schedule = False
elif model_arch in ["Lfm2ForCausalLM"]:
assert (
not self.enable_mamba_extra_buffer()
), f"mamba extra_buffer is not supported for {model_arch} model"
if not self.disable_radix_cache:
logger.warning(
"Disabling overlap schedule since mamba no_buffer is not compatible with "
"overlap schedule, try to use --disable-radix-cache if overlap schedule is necessary"
)
self.disable_overlap_schedule = True
if is_sm100_supported():
if self.attention_backend is None:
self.attention_backend = "flashinfer"
logger.info(
f"Use flashinfer as attention backend on sm100 for {model_arch}"
)
if self.attention_backend == "trtllm_mha":
logger.warning(
"Disabling radix cache since trtllm_mha does not support page_size = 1, which is required by MambaRadixCache. "
"Try to use --attention-backend flashinfer if radix cache is necessary."
)
self.disable_radix_cache = True
self.disable_overlap_schedule = False
assert self.attention_backend != "triton", (
f"{model_arch} does not support triton attention backend, "
"as the first layer might not be an attention layer"
)
if envs.SGLANG_EMBEDDINGS_SPARSE_HEAD.is_set():
self.disable_overlap_schedule = True