class EagleProposer:
def __init__(
self,
vllm_config: VllmConfig,
device: torch.device,
runner=None,
):
self.vllm_config = vllm_config
self.speculative_config = vllm_config.speculative_config
self.draft_model_config = self.speculative_config.draft_model_config
self.method = self.speculative_config.method
self.runner = runner
self.dtype = vllm_config.model_config.dtype
self.max_model_len = vllm_config.model_config.max_model_len
self.block_size = vllm_config.cache_config.block_size
self.num_speculative_tokens = (
self.speculative_config.num_speculative_tokens)
self.max_num_tokens = (
vllm_config.scheduler_config.max_num_batched_tokens)
# We need to get the hidden size from the draft model config because
# the draft model's hidden size can be different from the target model's
# hidden size (e.g., Llama 3.3 70B).
self.hidden_size = self.draft_model_config.get_hidden_size()
self.use_cuda_graph = (self.vllm_config.compilation_config.level
== CompilationLevel.PIECEWISE and
not self.vllm_config.model_config.enforce_eager)
self.cudagraph_batch_sizes = list(
reversed(
self.vllm_config.compilation_config.cudagraph_capture_sizes))
# persistent buffers for cuda graph
self.input_ids = torch.zeros(self.max_num_tokens,
dtype=torch.int32,
device=device)
self.positions = torch.zeros(self.max_num_tokens,
dtype=torch.int64,
device=device)
self.hidden_states = torch.zeros(
(self.max_num_tokens, self.hidden_size),
dtype=self.dtype,
device=device)
# We need +1 here because the arange is used to set query_start_loc,
# which has one more element than batch_size.
self.arange = torch.arange(vllm_config.scheduler_config.max_num_seqs +
1,
device=device,
dtype=torch.int32)
def propose(
self,
# [num_tokens]
target_token_ids: torch.Tensor,
# [num_tokens]
target_positions: torch.Tensor,
# [num_tokens, hidden_size]
target_hidden_states: torch.Tensor,
# [num_tokens]
target_slot_mapping: torch.Tensor,
# [batch_size]
next_token_ids: torch.Tensor,
# [batch_size + 1] starting with 0
cu_num_tokens: torch.Tensor,
# [batch_size, max_num_blocks_per_req]
block_table: torch.Tensor,
sampling_metadata: SamplingMetadata,
) -> torch.Tensor:
num_tokens = target_token_ids.shape[0]
batch_size = next_token_ids.shape[0]
last_token_indices = cu_num_tokens[1:] - 1
if self.method == "eagle3":
assert isinstance(self.model, Eagle3LlamaForCausalLM)
target_hidden_states = self.model.combine_hidden_states(
target_hidden_states)
assert target_hidden_states.shape[-1] == self.hidden_size
# Shift the input ids by one token.
# E.g., [a1, b1, b2, c1, c2, c3] -> [b1, b2, c1, c2, c3, c3]
self.input_ids[:num_tokens - 1] = target_token_ids[1:]
# Replace the last token with the next token.
# E.g., [b1, b2, c1, c2, c3, c3] -> [a2, b2, b3, c2, c3, c4]
self.input_ids[last_token_indices] = next_token_ids
# FA requires seq_len to have dtype int32.
seq_lens = (target_positions[last_token_indices] + 1).int()
if self.method in ["eagle", "eagle3"]:
# FIXME(woosuk): The below two ops cause synchronization. Optimize.
max_seq_len = seq_lens.max().item()
max_num_tokens = (cu_num_tokens[1:] -
cu_num_tokens[:-1]).max().item()
attn_metadata = FlashAttentionMetadata(
num_actual_tokens=num_tokens,
max_query_len=max_num_tokens,
query_start_loc=cu_num_tokens,
max_seq_len=max_seq_len,
seq_lens=seq_lens,
block_table=block_table,
slot_mapping=target_slot_mapping,
# TODO(woosuk): Support cascade attention.
use_cascade=False,
common_prefix_len=0,
cu_prefix_query_lens=None,
prefix_kv_lens=None,
suffix_kv_lens=None,
)
elif self.method == "deepseek_mtp":
query_lens = cu_num_tokens[1:] - cu_num_tokens[:-1]
max_query_len = query_lens.max().item()
common_attn_metadata = CommonAttentionMetadata(
query_start_loc=cu_num_tokens,
seq_lens=seq_lens,
num_reqs=batch_size,
num_actual_tokens=num_tokens,
max_query_len=max_query_len,
)
assert self.runner is not None
# FIXME: need to consider multiple kv_cache_groups
attn_metadata = self.runner.attn_metadata_builders[0].build(
common_prefix_len=0,
common_attn_metadata=common_attn_metadata,
)
else:
raise ValueError(f"Unsupported method: {self.method}")
# At this moment, we assume all eagle layers belong to the same KV
# cache group, thus using the same attention metadata.
per_layer_attn_metadata = {}
for layer_name in self.attn_layer_names:
per_layer_attn_metadata[layer_name] = attn_metadata
if self.use_cuda_graph and \
num_tokens <= self.cudagraph_batch_sizes[-1]:
num_input_tokens = self.vllm_config.pad_for_cudagraph(num_tokens)
else:
num_input_tokens = num_tokens
# copy inputs to buffer for cudagraph
self.positions[:num_tokens] = target_positions
self.hidden_states[:num_tokens] = target_hidden_states
with set_forward_context(per_layer_attn_metadata,
self.vllm_config,
num_tokens=num_input_tokens):
ret_hidden_states = self.model(
self.input_ids[:num_input_tokens],
self.positions[:num_input_tokens],
self.hidden_states[:num_input_tokens],
)
if self.method == "deepseek_mtp":
last_hidden_states = ret_hidden_states
else:
last_hidden_states, hidden_states = ret_hidden_states
sample_hidden_states = last_hidden_states[last_token_indices]
logits = self.model.compute_logits(sample_hidden_states, None)
draft_token_ids = logits.argmax(dim=-1)
# Early exit if there is only one draft token to be generated.
if self.num_speculative_tokens == 1:
# [batch_size, 1]
return draft_token_ids.view(-1, 1)
# TODO: Currently, MTP module released by deepseek only has
# one layer. Adapt this code to support multiple layers once
# there's a multi-layer MTP module.
# Generate the remaining draft tokens.
draft_token_ids_list = [draft_token_ids]
positions = target_positions[last_token_indices]
hidden_states = hidden_states[last_token_indices]
if self.use_cuda_graph and \
batch_size <= self.cudagraph_batch_sizes[-1]:
input_batch_size = self.vllm_config.pad_for_cudagraph(batch_size)
else:
input_batch_size = batch_size
attn_metadata.num_actual_tokens = batch_size
attn_metadata.max_query_len = 1
attn_metadata.query_start_loc = self.arange[:batch_size + 1]
for _ in range(self.num_speculative_tokens - 1):
# Update the inputs.
# cast to int32 is crucial when eagle model is compiled.
# tensor.argmax() returns int64 by default.
input_ids = draft_token_ids_list[-1].int()
positions += 1
# NOTE(woosuk): We should handle the case where the draft model
# generates tokens beyond the max model length. Since it is complex
# to remove such requests from the batch, we keep them in the batch
# but adjust the position ids and slot mappings to avoid the
# out-of-range access during the model execution. The draft tokens
# generated with this adjustment should be ignored.
exceeds_max_model_len = positions >= self.max_model_len
# Mask out the position ids that exceed the max model length.
# Otherwise, we may get out-of-range error in RoPE.
clamped_positions = torch.where(exceeds_max_model_len, 0,
positions)
# Increment the sequence lengths.
attn_metadata.max_seq_len += 1
attn_metadata.seq_lens += 1
# Consider max model length.
attn_metadata.max_seq_len = min(attn_metadata.max_seq_len,
self.max_model_len)
# For the requests that exceed the max model length, we set the
# sequence length to 1 to minimize their overheads in attention.
attn_metadata.seq_lens.masked_fill_(exceeds_max_model_len, 1)
# Compute the slot mapping.
block_numbers = clamped_positions // self.block_size
block_ids = block_table.gather(dim=1,
index=block_numbers.view(-1, 1))
block_ids = block_ids.view(-1)
attn_metadata.slot_mapping = (block_ids * self.block_size +
clamped_positions % self.block_size)
# Mask out the slot mappings that exceed the max model length.
# Otherwise, the KV cache will be inadvertently updated with the
# padding tokens.
attn_metadata.slot_mapping.masked_fill_(exceeds_max_model_len,
PADDING_SLOT_ID)
# copy inputs to buffer for cudagraph
self.input_ids[:batch_size] = input_ids
self.positions[:batch_size] = clamped_positions
self.hidden_states[:batch_size] = hidden_states
# Run the model.
with set_forward_context(per_layer_attn_metadata,
self.vllm_config,
num_tokens=input_batch_size):
last_hidden_states, hidden_states = self.model(
self.input_ids[:input_batch_size],
self.positions[:input_batch_size],
self.hidden_states[:input_batch_size],
)
hidden_states = hidden_states[:batch_size]
logits = self.model.compute_logits(last_hidden_states[:batch_size],
None)
# TODO(wenlong): get more than one token for tree attention
draft_token_ids = logits.argmax(dim=-1)
draft_token_ids_list.append(draft_token_ids)
# [batch_size, num_speculative_tokens]
draft_token_ids = torch.stack(draft_token_ids_list, dim=1)
return draft_token_ids
@staticmethod
def prepare_inputs(
# [batch_size + 1]
cu_target_query_lens: torch.Tensor,
# [batch_size]
num_rejected_tokens: torch.Tensor,
num_tokens: int,
) -> tuple[torch.Tensor, torch.Tensor]:
# cu_target_query_lens: [0, a, a + b, a + b + c]
# num_rejected_tokens: [n1, n2, n3]
# num_tokens_per_req: [a - n1, b - n2, c - n3]
# cu_num_tokens: [0, a - n1, a + b - n1 - n2, a + b + c - n1 - n2 - n3]
# token_indices: [0, 1, ..., a - n1 - 1,
# a, a + 1, ..., a + b - n2 - 1,
# a + b, a + b + 1, ..., a + b + c - n3 - 1]
# [0, a, a + b, a + b + c] -> [a, b, c]
query_len_per_req = (cu_target_query_lens[1:] -
cu_target_query_lens[:-1])
# [a, b, c] -> [a - n1, b - n2, c - n3]
num_tokens_per_req = query_len_per_req - num_rejected_tokens
# [a - n1, b - n2, c - n3] ->
# [0, a - n1, a + b - n1 - n2, a + b + c - n1 - n2 - n3]
cu_num_tokens = torch.zeros_like(cu_target_query_lens)
torch.cumsum(num_tokens_per_req, dim=0, out=cu_num_tokens[1:])
token_indices = torch.empty(
num_tokens,
dtype=torch.int32,
device=cu_target_query_lens.device,
)
batch_size = num_rejected_tokens.shape[0]
BLOCK_SIZE = 1024
prepare_eagle_input_kernel[(batch_size, )](
token_indices,
cu_target_query_lens,
cu_num_tokens,
BLOCK_SIZE=BLOCK_SIZE,
)
return cu_num_tokens, token_indices
def load_model(self, target_model: nn.Module) -> None:
draft_model_config = \
self.vllm_config.speculative_config.draft_model_config
target_attn_layer_names = set(
get_layers_from_vllm_config(self.vllm_config, Attention).keys())
from vllm.compilation.backends import set_model_tag
with set_model_tag("eagle_head"):
self.model = get_model(vllm_config=self.vllm_config,
model_config=draft_model_config)
draft_attn_layer_names = (
get_layers_from_vllm_config(self.vllm_config, Attention).keys() -
target_attn_layer_names)
self.attn_layer_names = list(draft_attn_layer_names)
if supports_multimodal(target_model):
# handle multimodality
self.model.config.image_token_index = (
target_model.config.image_token_index)
target_language_model = target_model.get_language_model()
else:
target_language_model = target_model
# share embed_tokens with the target model if needed
if get_pp_group().world_size == 1 \
and self.model.model.embed_tokens.weight.shape \
== target_language_model.model.embed_tokens.weight.shape:
logger.info(
"Assuming the EAGLE head shares the same vocab embedding" \
" with the target model."
)
del self.model.model.embed_tokens
self.model.model.embed_tokens = (
target_language_model.model.embed_tokens)
else:
logger.info(
"The EAGLE head's vocab embedding will be loaded separately" \
" from the target model."
)
# share lm_head with the target model if needed
# some model definition do not define lm_head explicitly
# and reuse embed_tokens for lm_head, e.g., CohereForCausalLM
if self.vllm_config.speculative_config.method != "eagle3" and \
hasattr(target_language_model, "lm_head"):
logger.info("Loading EAGLE LM head weights from the target model.")
self.model.lm_head = target_language_model.lm_head
@torch.inference_mode()
def dummy_run(
self,
num_tokens: int,
) -> None:
with set_forward_context(None, self.vllm_config,
num_tokens=num_tokens):
self.model(
self.input_ids[:num_tokens],
self.positions[:num_tokens],
self.hidden_states[:num_tokens],
)
def validate_same_kv_cache_group(self,
kv_cache_config: KVCacheConfig) -> None:
"""
Validate that all eagle layers belong to the same KVCacheGroup.
Need this assumption to ensure all eagle layers can use the
same AttentionMetadata.
May extend to multiple AttentionMetadata in the future.
"""
kv_cache_groups: dict[str, int] = {}
for id, kv_cache_group in enumerate(kv_cache_config.kv_cache_groups):
for layer_name in kv_cache_group.layer_names:
kv_cache_groups[layer_name] = id
assert len(
set([
kv_cache_groups[layer_name]
for layer_name in self.attn_layer_names
])
) == 1, "All eagle layers should belong to the same kv cache group"