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A high-throughput and memory-efficient inference and serving engine for LLMs

Mirrored from https://github.com/tduncan-lum/Nvidia-Optimization-Stack---VLLM.git

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[Model] Re-implement Qwen3Omni Audio Encoder (#32167)

Signed-off-by: Roger Wang <hey@rogerw.io>

Roger Wang committed Jan 13, 2026 at 23:40 UTC b8199f604931012c433e018980aac22d44ad30b5
1 file changed +428 -29
vllm/model_executor/models/qwen3_omni_moe_thinker.py
+428 -29
@@ -31,29 +31,34 @@ import torch
31 import torch.nn as nn
32 import torch.nn.functional as F
33 from packaging.version import Version
34 -from transformers import PretrainedConfig
35 -from transformers import __version__ as TRANSFORMERS_VERSION
34 from transformers.feature_extraction_utils import BatchFeature
35 from transformers.models.qwen3_omni_moe.configuration_qwen3_omni_moe import (
36 + Qwen3OmniMoeAudioEncoderConfig,
37 Qwen3OmniMoeConfig,
38 Qwen3OmniMoeThinkerConfig,
39 )
41 -from transformers.models.qwen3_omni_moe.modeling_qwen3_omni_moe import (
42 - Qwen3OmniMoeAudioEncoder,
43 -)
40 from transformers.models.qwen3_omni_moe.processing_qwen3_omni_moe import (
41 Qwen3OmniMoeProcessor,
42 )
43 from transformers.models.whisper import WhisperFeatureExtractor
44
45 +# isort: off
46 +from transformers import PretrainedConfig
47 +from transformers import __version__ as TRANSFORMERS_VERSION
48 +# isort: on
49 +
50 from vllm.compilation.decorators import support_torch_compile
51 from vllm.config import MultiModalConfig, VllmConfig
51 -from vllm.distributed import get_pp_group
52 +from vllm.distributed import get_pp_group, get_tensor_model_parallel_world_size
53 from vllm.logger import init_logger
54 from vllm.model_executor.layers.activation import _ACTIVATION_REGISTRY
55 +from vllm.model_executor.layers.attention.mm_encoder_attention import (
56 + MMEncoderAttention,
57 +)
58 from vllm.model_executor.layers.conv import Conv3dLayer
59 from vllm.model_executor.layers.linear import (
60 ColumnParallelLinear,
61 + QKVParallelLinear,
62 RowParallelLinear,
63 )
64 from vllm.model_executor.layers.logits_processor import LogitsProcessor
@@ -104,11 +109,6 @@ from .vision import (
109 get_vit_attn_backend,
110 )
111
107 -try:
108 - import flash_attn
109 -except (ImportError, ModuleNotFoundError):
110 - flash_attn = None
111 -
112 logger = init_logger(__name__)
113
114
@@ -121,6 +121,415 @@ def _get_feat_extract_output_lengths(input_lengths: torch.Tensor):
121 return output_lengths
122
123
124 +# ============= Audio Encoder Components =============
125 +
126 +
127 +class SinusoidsPositionEmbedding(nn.Module):
128 + """Sinusoidal position embedding for audio encoder."""
129 +
130 + def __init__(self, length: int, channels: int, max_timescale: int = 10000):
131 + super().__init__()
132 + self.length = length
133 + self.channels = channels
134 + self.max_timescale = max_timescale
135 +
136 + if channels % 2 != 0:
137 + raise ValueError("SinusoidsPositionEmbedding needs even channels input")
138 +
139 + log_timescale_increment = np.log(max_timescale) / (channels // 2 - 1)
140 + inv_timescales = torch.exp(
141 + -log_timescale_increment * torch.arange(channels // 2).float()
142 + )
143 + scaled_time = (
144 + torch.arange(length)[:, np.newaxis] * inv_timescales[np.newaxis, :]
145 + )
146 + positional_embedding = torch.cat(
147 + [torch.sin(scaled_time), torch.cos(scaled_time)], dim=1
148 + )
149 + self.register_buffer(
150 + "positional_embedding", positional_embedding, persistent=False
151 + )
152 +
153 + def forward(self, seqlen: int) -> torch.Tensor:
154 + return self.positional_embedding[:seqlen, :]
155 +
156 +
157 +class Qwen3OmniMoeAudioAttention(nn.Module):
158 + """Multi-headed attention for Qwen3-Omni Audio Encoder using MMEncoderAttention."""
159 +
160 + def __init__(
161 + self,
162 + config: Qwen3OmniMoeAudioEncoderConfig,
163 + multimodal_config: MultiModalConfig | None = None,
164 + prefix: str = "",
165 + ):
166 + super().__init__()
167 + self.embed_dim = config.d_model
168 + self.num_heads = config.encoder_attention_heads
169 + self.head_dim = self.embed_dim // self.num_heads
170 + tp_size = get_tensor_model_parallel_world_size()
171 + self.num_local_heads = self.num_heads // tp_size
172 +
173 + if (self.head_dim * self.num_heads) != self.embed_dim:
174 + raise ValueError(
175 + f"embed_dim must be divisible by num_heads (got `embed_dim`: "
176 + f"{self.embed_dim} and `num_heads`: {self.num_heads})."
177 + )
178 +
179 + self.scaling = self.head_dim**-0.5
180 +
181 + self.qkv = QKVParallelLinear(
182 + hidden_size=self.embed_dim,
183 + head_size=self.head_dim,
184 + total_num_heads=self.num_heads,
185 + total_num_kv_heads=self.num_heads,
186 + bias=True,
187 + prefix=f"{prefix}.qkv",
188 + )
189 +
190 + self.out_proj = RowParallelLinear(
191 + input_size=self.embed_dim,
192 + output_size=self.embed_dim,
193 + bias=True,
194 + prefix=f"{prefix}.out_proj",
195 + )
196 +
197 + self.attn = MMEncoderAttention(
198 + num_heads=self.num_local_heads,
199 + head_size=self.head_dim,
200 + scale=self.scaling,
201 + multimodal_config=multimodal_config,
202 + )
203 +
204 + def forward(
205 + self,
206 + hidden_states: torch.Tensor,
207 + cu_seqlens: torch.Tensor,
208 + max_seqlen: torch.Tensor | None,
209 + ) -> torch.Tensor:
210 + seq_length, _ = hidden_states.size()
211 + qkv, _ = self.qkv(hidden_states)
212 + q, k, v = qkv.chunk(3, dim=-1)
213 + q = q.view(1, seq_length, -1, self.head_dim)
214 + k = k.view(1, seq_length, -1, self.head_dim)
215 + v = v.view(1, seq_length, -1, self.head_dim)
216 +
217 + attn_output = self.attn(
218 + query=q,
219 + key=k,
220 + value=v,
221 + cu_seqlens=cu_seqlens,
222 + max_seqlen=max_seqlen,
223 + )
224 +
225 + attn_output = attn_output.view(seq_length, -1)
226 + output, _ = self.out_proj(attn_output)
227 + return output
228 +
229 +
230 +class Qwen3OmniMoeAudioEncoderLayer(nn.Module):
231 + """Transformer encoder layer for Qwen3-Omni Audio Encoder."""
232 +
233 + def __init__(
234 + self,
235 + config: Qwen3OmniMoeAudioEncoderConfig,
236 + multimodal_config: MultiModalConfig | None = None,
237 + prefix: str = "",
238 + ):
239 + super().__init__()
240 + self.embed_dim = config.d_model
241 + self.self_attn = Qwen3OmniMoeAudioAttention(
242 + config, multimodal_config=multimodal_config, prefix=f"{prefix}.self_attn"
243 + )
244 + self.self_attn_layer_norm = nn.LayerNorm(self.embed_dim)
245 + self.activation_fn = _ACTIVATION_REGISTRY[config.activation_function]
246 + self.fc1 = ColumnParallelLinear(
247 + self.embed_dim,
248 + config.encoder_ffn_dim,
249 + bias=True,
250 + prefix=f"{prefix}.fc1",
251 + )
252 + self.fc2 = RowParallelLinear(
253 + config.encoder_ffn_dim,
254 + self.embed_dim,
255 + bias=True,
256 + prefix=f"{prefix}.fc2",
257 + )
258 + self.final_layer_norm = nn.LayerNorm(self.embed_dim)
259 +
260 + def forward(
261 + self,
262 + hidden_states: torch.Tensor,
263 + cu_seqlens: torch.Tensor,
264 + max_seqlen: torch.Tensor | None,
265 + ) -> torch.Tensor:
266 + """
267 + Args:
268 + hidden_states: Input tensor of shape (seq_len, hidden_size)
269 + cu_seqlens: Cumulative sequence lengths
270 + max_seqlen: Maximum sequence length in the batch
271 + """
272 + residual = hidden_states
273 + hidden_states = self.self_attn_layer_norm(hidden_states)
274 + hidden_states = self.self_attn(
275 + hidden_states=hidden_states,
276 + cu_seqlens=cu_seqlens,
277 + max_seqlen=max_seqlen,
278 + )
279 + hidden_states = residual + hidden_states
280 +
281 + residual = hidden_states
282 + hidden_states = self.final_layer_norm(hidden_states)
283 + hidden_states, _ = self.fc1(hidden_states)
284 + hidden_states = self.activation_fn(hidden_states)
285 + hidden_states, _ = self.fc2(hidden_states)
286 + hidden_states = residual + hidden_states
287 +
288 + # Clamp for numerical stability with fp16
289 + if hidden_states.dtype == torch.float16:
290 + clamp_value = torch.finfo(hidden_states.dtype).max - 1000
291 + hidden_states = torch.clamp(
292 + hidden_states, min=-clamp_value, max=clamp_value
293 + )
294 +
295 + return hidden_states
296 +
297 +
298 +class Qwen3OmniMoeAudioEncoder(nn.Module):
299 + """vLLM-native Qwen3-Omni Audio Encoder."""
300 +
301 + def __init__(
302 + self,
303 + config: Qwen3OmniMoeAudioEncoderConfig,
304 + multimodal_config: MultiModalConfig | None = None,
305 + prefix: str = "",
306 + ):
307 + super().__init__()
308 +
309 + embed_dim = config.d_model
310 + self.num_mel_bins = config.num_mel_bins
311 + self.max_source_positions = config.max_source_positions
312 + self.n_window = config.n_window
313 + self.n_window_infer = config.n_window_infer
314 + self.conv_chunksize = config.conv_chunksize
315 +
316 + # Position embedding
317 + self.positional_embedding = SinusoidsPositionEmbedding(
318 + self.max_source_positions, embed_dim
319 + )
320 +
321 + # Convolutional layers for mel-spectrogram processing
322 + self.conv2d1 = nn.Conv2d(1, config.downsample_hidden_size, 3, 2, padding=1)
323 + self.conv2d2 = nn.Conv2d(
324 + config.downsample_hidden_size,
325 + config.downsample_hidden_size,
326 + 3,
327 + 2,
328 + padding=1,
329 + )
330 + self.conv2d3 = nn.Conv2d(
331 + config.downsample_hidden_size,
332 + config.downsample_hidden_size,
333 + 3,
334 + 2,
335 + padding=1,
336 + )
337 +
338 + conv_out_dim = config.downsample_hidden_size * (
339 + (((config.num_mel_bins + 1) // 2 + 1) // 2 + 1) // 2
340 + )
341 + self.conv_out = nn.Linear(conv_out_dim, config.d_model, bias=False)
342 +
343 + # Transformer encoder layers
344 + self.layers = nn.ModuleList(
345 + [
346 + Qwen3OmniMoeAudioEncoderLayer(
347 + config,
348 + multimodal_config=multimodal_config,
349 + prefix=f"{prefix}.layers.{i}",
350 + )
351 + for i in range(config.encoder_layers)
352 + ]
353 + )
354 +
355 + # Output layers
356 + self.ln_post = nn.LayerNorm(config.d_model)
357 + self.proj1 = nn.Linear(config.d_model, config.d_model)
358 + self.act = _ACTIVATION_REGISTRY[config.activation_function]
359 + self.proj2 = nn.Linear(config.d_model, config.output_dim)
360 +
361 + # Get attention backend
362 + attn_backend_override = (
363 + multimodal_config.mm_encoder_attn_backend
364 + if multimodal_config is not None
365 + else None
366 + )
367 + self.attn_backend = get_vit_attn_backend(
368 + head_size=config.d_model // config.encoder_attention_heads,
369 + dtype=torch.get_default_dtype(),
370 + attn_backend_override=attn_backend_override,
371 + )
372 +
373 + def compute_attn_mask_seqlen(self, cu_seqlens: torch.Tensor) -> torch.Tensor | None:
374 + """Compute max_seqlen only for flash attention backends."""
375 + max_seqlen = None
376 + if self.attn_backend in {
377 + AttentionBackendEnum.FLASH_ATTN,
378 + AttentionBackendEnum.ROCM_AITER_FA,
379 + }:
380 + max_seqlen = (cu_seqlens[1:] - cu_seqlens[:-1]).max()
381 + return max_seqlen
382 +
383 + @property
384 + def dtype(self) -> torch.dtype:
385 + return self.conv2d1.weight.dtype
386 +
387 + @property
388 + def device(self) -> torch.device:
389 + return self.conv2d1.weight.device
390 +
391 + def forward(
392 + self,
393 + input_features: torch.Tensor,
394 + feature_lens: torch.Tensor,
395 + aftercnn_lens: torch.Tensor,
396 + ):
397 + # Compute chunk information
398 + chunk_num = torch.ceil(feature_lens / (self.n_window * 2)).long()
399 +
400 + chunk_lengths = torch.tensor(
401 + [self.n_window * 2] * chunk_num.sum(),
402 + dtype=torch.long,
403 + device=feature_lens.device,
404 + )
405 + tail_chunk_index = F.pad(chunk_num, (1, 0), value=-1).cumsum(0)[1:]
406 + chunk_lengths[tail_chunk_index] = feature_lens % (self.n_window * 2)
407 + chunk_lengths[chunk_lengths == 0] = self.n_window * 2
408 +
409 + # Split input features into chunks and pad
410 + chunk_list = input_features.T.split(chunk_lengths.tolist(), dim=0)
411 + padded_feature = nn.utils.rnn.pad_sequence(
412 + chunk_list, batch_first=True
413 + ).transpose(1, 2)
414 +
415 + # Compute feature lengths after CNN
416 + feature_lens_after_cnn = self._get_cnn_output_lengths(chunk_lengths)
417 + # Vectorized mask creation: avoid creating many small tensors
418 + max_len_after_cnn = feature_lens_after_cnn.max().item()
419 + indices = torch.arange(max_len_after_cnn, device=padded_feature.device)
420 + padded_mask_after_cnn = indices.unsqueeze(0) < feature_lens_after_cnn.unsqueeze(
421 + 1
422 + )
423 +
424 + # Add channel dimension for conv2d
425 + padded_feature = padded_feature.unsqueeze(1)
426 +
427 + # Apply convolutional layers (chunk if needed to avoid OOM)
428 + if padded_feature.size(0) <= self.conv_chunksize:
429 + # Fast path: no chunking needed
430 + padded_embed = F.gelu(self.conv2d1(padded_feature))
431 + padded_embed = F.gelu(self.conv2d2(padded_embed))
432 + padded_embed = F.gelu(self.conv2d3(padded_embed))
433 + else:
434 + # Chunked processing to avoid OOM
435 + padded_embeds = []
436 + for chunk in padded_feature.split(self.conv_chunksize, dim=0):
437 + padded_embed = F.gelu(self.conv2d1(chunk))
438 + padded_embed = F.gelu(self.conv2d2(padded_embed))
439 + padded_embed = F.gelu(self.conv2d3(padded_embed))
440 + padded_embeds.append(padded_embed)
441 + padded_embed = torch.cat(padded_embeds, dim=0)
442 +
443 + # (batch, channels, freq, time) -> (batch, time, channels*freq)
444 + b, c, f, t = padded_embed.size()
445 + padded_embed = self.conv_out(
446 + padded_embed.permute(0, 3, 1, 2).contiguous().view(b, t, c * f)
447 + )
448 +
449 + # Add positional embedding
450 + positional_embedding = (
451 + self.positional_embedding.positional_embedding[: padded_embed.shape[1], :]
452 + .unsqueeze(0)
453 + .to(padded_embed.dtype)
454 + )
455 + padded_embed = padded_embed + positional_embedding
456 +
457 + # Extract valid hidden states and compute cu_seqlens
458 + hidden_states = padded_embed[padded_mask_after_cnn]
459 +
460 + # Compute cumulative sequence lengths for chunked attention
461 + cu_chunk_lens = [0]
462 + window_aftercnn = padded_mask_after_cnn.shape[-1] * (
463 + self.n_window_infer // (self.n_window * 2)
464 + )
465 + # Use tolist() for efficient batch conversion from tensor to Python
466 + for cnn_len in aftercnn_lens.tolist():
467 + num_full_chunks = cnn_len // window_aftercnn
468 + remainder = cnn_len % window_aftercnn
469 + cu_chunk_lens.extend([window_aftercnn] * num_full_chunks)
470 + if remainder:
471 + cu_chunk_lens.append(remainder)
472 + cu_seqlens = torch.tensor(cu_chunk_lens, device=aftercnn_lens.device).cumsum(
473 + -1, dtype=torch.int32
474 + )
475 +
476 + max_seqlen = self.compute_attn_mask_seqlen(cu_seqlens)
477 +
478 + # Apply transformer layers
479 + for encoder_layer in self.layers:
480 + hidden_states = encoder_layer(
481 + hidden_states,
482 + cu_seqlens,
483 + max_seqlen,
484 + )
485 +
486 + # Apply output layers
487 + hidden_states = self.ln_post(hidden_states)
488 + hidden_states = self.proj1(hidden_states)
489 + hidden_states = self.act(hidden_states)
490 + hidden_states = self.proj2(hidden_states)
491 +
492 + return hidden_states
493 +
494 + def _get_cnn_output_lengths(self, input_lengths: torch.Tensor) -> torch.Tensor:
495 + """Compute output lengths after the three conv2d layers."""
496 + lengths = input_lengths
497 + for _ in range(3):
498 + lengths = (lengths - 1) // 2 + 1
499 + return lengths
500 +
501 + def load_weights(self, weights: Iterable[tuple[str, torch.Tensor]]) -> set[str]:
502 + """Load weights with mapping from HuggingFace format."""
503 + stacked_params_mapping = [
504 + # (param_name, shard_name, shard_id)
505 + ("self_attn.qkv.", "self_attn.q_proj.", "q"),
506 + ("self_attn.qkv.", "self_attn.k_proj.", "k"),
507 + ("self_attn.qkv.", "self_attn.v_proj.", "v"),
508 + ]
509 + params_dict = dict(self.named_parameters(remove_duplicate=False))
510 + loaded_params: set[str] = set()
511 +
512 + for name, loaded_weight in weights:
513 + for param_name, weight_name, shard_id in stacked_params_mapping:
514 + if weight_name not in name:
515 + continue
516 + name = name.replace(weight_name, param_name)
517 +
518 + param = params_dict[name]
519 + weight_loader = param.weight_loader
520 + weight_loader(param, loaded_weight, shard_id)
521 + break
522 + else:
523 + param = params_dict.get(name)
524 + if param is not None:
525 + weight_loader = getattr(
526 + param, "weight_loader", default_weight_loader
527 + )
528 + weight_loader(param, loaded_weight)
529 + loaded_params.add(name)
530 + return loaded_params
531 +
532 +
533 class Qwen3_VisionPatchEmbed(nn.Module):
534 def __init__(
535 self,
@@ -144,7 +553,7 @@ class Qwen3_VisionPatchEmbed(nn.Module):
553 )
554
555 def forward(self, x: torch.Tensor) -> torch.Tensor:
147 - L, C = x.shape
556 + L, _ = x.shape
557 x = x.view(L, -1, self.temporal_patch_size, self.patch_size, self.patch_size)
558 x = self.proj(x).view(L, self.hidden_size)
559 return x
@@ -224,7 +633,7 @@ class Qwen3_VisionBlock(nn.Module):
633 cu_seqlens: torch.Tensor,
634 rotary_pos_emb_cos: torch.Tensor,
635 rotary_pos_emb_sin: torch.Tensor,
227 - max_seqlen: torch.Tensor, # Only used for Flash Attention
636 + max_seqlen: torch.Tensor | None, # Only used for Flash Attention
637 ) -> torch.Tensor:
638 x = x + self.attn(
639 self.norm1(x),
@@ -1142,12 +1551,11 @@ class Qwen3OmniMoeConditionalGenerationMixin(Qwen2_5OmniConditionalGenerationMix
1551
1552 audio_output_lengths = _get_feat_extract_output_lengths(audio_feature_lengths)
1553
1145 - audio_outputs = self.audio_tower(
1554 + audio_features = self.audio_tower(
1555 input_features.to(self.audio_tower.dtype),
1556 feature_lens=audio_feature_lengths,
1557 aftercnn_lens=audio_output_lengths,
1558 )
1150 - audio_features = audio_outputs.last_hidden_state
1559 return audio_features.split(audio_output_lengths.tolist())
1560
1561
@@ -1205,20 +1613,11 @@ class Qwen3OmniMoeThinkerForConditionalGeneration(
1613 self.config = thinker_config
1614 self.multimodal_config = multimodal_config
1615
1208 - # force "use_flash_attention_2=True" to audio tower to align
1209 - # the results.
1210 - if flash_attn is not None:
1211 - audio_config = thinker_config.audio_config
1212 - audio_config._attn_implementation_autoset = True
1213 - audio_config._attn_implementation = "flash_attention_2"
1214 - else:
1215 - logger.warning(
1216 - "flash_attn is not available, the model may not yield the "
1217 - "exactly same result as the transformers implementation "
1218 - "in the audio tower part."
1219 - )
1220 -
1221 - self.audio_tower = Qwen3OmniMoeAudioEncoder(thinker_config.audio_config)
1616 + self.audio_tower = Qwen3OmniMoeAudioEncoder(
1617 + thinker_config.audio_config,
1618 + multimodal_config=multimodal_config,
1619 + prefix=maybe_prefix(prefix, "audio_tower"),
1620 + )
1621
1622 self.visual = Qwen3Omni_VisionTransformer(
1623 vision_config=thinker_config.vision_config,