Files
xc-llm-ascend/vllm_ascend/worker/v2/sample/gumbel.py
Ronald f1ffb5fb19 [Feature] adapt to uva buffer and main2main (#6657)
### What this PR does / why we need it?
vllm model runner v2 use uva buffer to prepare input data, but npu
doesn't support uva yet, this pr implement a uvawrapper class to mimic
gpu's uva backend. what's more, this pr make some modifications to adapt
to the newer main branch.

### Does this PR introduce _any_ user-facing change?
no
### How was this patch tested?
- vLLM main:
13397841ab

---------

Signed-off-by: Ronald1995 <ronaldautomobile@163.com>
2026-02-12 10:36:31 +08:00

129 lines
4.2 KiB
Python

# Adapt from https://github.com/vllm-project/vllm/blob/main/vllm/v1/worker/gpu/sample/gumbel.py.
# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
#
# Copyright (c) 2025 Huawei Technologies Co., Ltd. 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.
# This file is a part of the vllm-ascend project.
#
import torch
from vllm.triton_utils import tl, triton
@triton.jit
def _gumbel_sample_kernel(
local_argmax_ptr,
local_argmax_stride,
local_max_ptr,
local_max_stride,
logits_ptr,
logits_stride,
idx_mapping_ptr,
seeds_ptr,
pos_ptr,
temp_ptr,
vocab_size,
BLOCK_SIZE: tl.constexpr,
APPLY_TEMPERATURE: tl.constexpr,
):
batch_idx = tl.program_id(0)
req_state_idx = tl.load(idx_mapping_ptr + batch_idx)
block_idx = tl.program_id(1)
block = block_idx * BLOCK_SIZE + tl.arange(0, BLOCK_SIZE)
mask = block < vocab_size
logits = tl.load(
logits_ptr + batch_idx * logits_stride + block,
mask=mask,
other=float("-inf"),
)
logits = logits.to(tl.float32)
temp = tl.load(temp_ptr + req_state_idx).to(tl.float32)
if temp != 0.0:
# Calculate the seed for gumbel noise.
seed = tl.load(seeds_ptr + req_state_idx)
# NOTE(Ronald1995): change pos's dtype to tl.int32, because triton-ascend's
# compiler doesn't support unint64 of pos arg.
pos = tl.load(pos_ptr + batch_idx).to(tl.int32)
gumbel_seed = tl.randint(seed, pos)
# Generate gumbel noise.
# NOTE(Ronald1995): r is tl.float64 in vllm, change it to tl.float32,
# or triton-ascend's compiler will raise error.
r = tl.rand(gumbel_seed, block).to(tl.float32)
gumbel_noise = -tl.log(-tl.log(r + 1e-20) + 1e-20)
gumbel_noise = gumbel_noise.to(tl.float32)
# Apply temperature.
if APPLY_TEMPERATURE:
# NOTE(woosuk): Match the behavior of _temperature_kernel.
# E.g., if the kernel uses tl.div_rn, we should use tl.div_rn here too.
logits = logits / temp
# Apply gumbel noise.
logits = tl.where(mask, logits + gumbel_noise, float("-inf"))
idx = tl.argmax(logits, axis=0)
token_id = block_idx * BLOCK_SIZE + idx
value = tl.max(logits, axis=0)
tl.store(local_argmax_ptr + batch_idx * local_argmax_stride + block_idx, token_id)
tl.store(local_max_ptr + batch_idx * local_max_stride + block_idx, value)
def gumbel_sample(
logits: torch.Tensor, # [num_reqs, vocab_size]
idx_mapping: torch.Tensor, # [num_reqs]
temperature: torch.Tensor, # [num_reqs]
seed: torch.Tensor, # [num_reqs]
pos: torch.Tensor, # [num_reqs]
apply_temperature: bool,
) -> torch.Tensor:
num_reqs, vocab_size = logits.shape
BLOCK_SIZE = 1024
num_blocks = triton.cdiv(vocab_size, BLOCK_SIZE)
local_argmax = torch.empty(
num_reqs,
num_blocks,
dtype=torch.int64,
device=logits.device,
)
local_max = torch.empty(
num_reqs,
num_blocks,
dtype=torch.float32,
device=logits.device,
)
# TODO(Ronald1995): Optimize the performance of the kernel in npu.
_gumbel_sample_kernel[(num_reqs, num_blocks)](
local_argmax,
local_argmax.stride(0),
local_max,
local_max.stride(0),
logits,
logits.stride(0),
idx_mapping,
seed,
pos,
temperature,
vocab_size,
BLOCK_SIZE=BLOCK_SIZE,
APPLY_TEMPERATURE=apply_temperature,
)
# NOTE(woosuk): Use int64 for later indexing.
max_block_idx = local_max.argmax(dim=-1, keepdim=True)
sampled = local_argmax.gather(dim=-1, index=max_block_idx).view(-1)
return sampled