vllm/vllm/v1/spec_decode/medusa.py
Mark McLoughlin c6b636f9fb
[V1][Spec Decoding] Use model_loader.get_model() to load models (#18273)
Signed-off-by: Mark McLoughlin <markmc@redhat.com>
2025-05-23 02:05:44 +00:00

62 lines
2.0 KiB
Python

# SPDX-License-Identifier: Apache-2.0
import torch
import torch.nn as nn
from vllm.config import VllmConfig
from vllm.forward_context import set_forward_context
from vllm.logger import init_logger
from vllm.model_executor.model_loader import get_model
from vllm.v1.sample.metadata import SamplingMetadata
# Initialize logger
logger = init_logger(__name__)
class MedusaProposer:
"""
Medusa proposer class for generating token sequences
"""
def __init__(
self,
vllm_config: VllmConfig,
device: torch.device,
):
# Save config parameters
self.vllm_config = vllm_config
self.device = device
self.max_num_tokens = (
vllm_config.scheduler_config.max_num_batched_tokens)
self.hidden_size = vllm_config.speculative_config.\
draft_model_config.get_hidden_size(
)
self.dtype = vllm_config.model_config.dtype
def propose(
self,
target_hidden_states: torch.Tensor,
sampling_metadata: SamplingMetadata,
) -> torch.Tensor:
# Generate blocks and compute logits
blocks = self.model(target_hidden_states)
logits = self.model.compute_logits(blocks, None)
# Get draft tokens and transpose the result
draft_tokens = [logit.argmax(dim=-1).tolist() for logit in logits]
return [list(row) for row in zip(*draft_tokens)]
def load_model(self, target_model: nn.Module) -> None:
self.model = get_model(vllm_config=self.vllm_config,
model_config=self.vllm_config.
speculative_config.draft_model_config)
@torch.inference_mode()
def dummy_run(self, num_tokens: int) -> None:
hidden_states = torch.zeros((self.max_num_tokens, self.hidden_size),
dtype=self.dtype,
device=self.device)
with set_forward_context(None, self.vllm_config,
num_tokens=num_tokens):
self.model(hidden_states)