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Flan-T5 在昇腾 NPU 上的部署与应用

Ascend NPU PyTorch torch_npu CANN Status


目录

  • 模型介绍
  • 昇腾适配说明
  • 环境准备
  • 权重下载与转换
  • 推理部署指南
  • 训练微调指南
  • 性能数据
  • 验证结果
  • 常见问题 FAQ
  • 许可证信息

模型介绍

Flan-T5 简介

Flan-T5 是 Google 在 T5(Text-to-Text Transfer Transformer)架构基础上,通过 Flan(Fine-tuned Language Net)指令微调技术开发的序列到序列(Seq2Seq)模型。该模型在 1000 余种多样化指令任务上完成微调,具备卓越的零样本(Zero-Shot)和少样本(Few-Shot)泛化能力。

架构特点

特性说明
架构类型编码器-解码器(Transformer)
注意力机制相对位置编码(Relative Position Bias)
归一化层归一化(pre-LN)
激活函数门控 GELU(前馈网络)
位置编码相对位置桶(Relative Attention Buckets)
任务格式文本到文本统一框架

参数规模

模型版本d_model编码器层数解码器层数注意力头数d_ff参数量
flan-t5-small5128861,02477M
flan-t5-base7681212122,048248M
flan-t5-large1,0242424162,816783M
flan-t5-xl2,0482424325,1202.85B
flan-t5-xxl4,09624246410,24011.3B

注意:当前验证基于 flan-t5-base 完成,其余规模模型理论上完全兼容,可直接复用本指南。

支持任务

  • 机器翻译(Translation)
  • 文本摘要(Summarization)
  • 问答系统(Question Answering)
  • 自然语言推理(NLI)
  • 情感分析(Sentiment Analysis)
  • 代码生成与修复(Code Generation)

昇腾适配说明

适配版本

组件版本号说明
驱动(Driver)25.5.2通过 npu-smi 查询版本
CANN 工具包8.5.1昇腾计算架构
Python3.11.14推荐版本
PyTorch2.9.0+cpu官方适配版本
torch_npu2.9.0.post1昇腾 PyTorch 插件
Transformers4.57.6HuggingFace 库
ModelScope1.35.3国内模型下载通道

硬件要求

项目最低配置推荐配置
NPU1x Ascend 310P1x Ascend 910 或 910B
CPUARM64 / x86_64ARM64 (鲲鹏 920)
内存16 GB32 GB+
HBM8 GB32 GB+ (910 系列)
磁盘50 GB100 GB+

适配状态

功能状态备注
模型加载✅ 已验证T5ForConditionalGeneration
FP32 推理✅ 已验证精度无损
FP16 推理✅ 已验证推荐,速度提升明显
文本生成 (Greedy)✅ 已验证model.generate()
文本生成 (Beam Search)✅ 已验证num_beams=4
训练 (Fine-tuning)✅ 已验证前向 + 反向 + 优化器
多卡训练⚠️ 待验证torch.distributed 理论上支持
量化推理⚠️ 待验证torch.ao.quantization
vLLM 部署❌ 不支持vLLM 当前仅支持 Decoder-only 模型

架构说明:Flan-T5 为 Encoder-Decoder 结构,因此 不适用 vLLM 推理框架。推荐直接使用 PyTorch + torch_npu 原生推理与训练。


环境准备

1. 驱动与固件检查

# 查询 NPU 状态
npu-smi info

# 预期输出示例
+------------------------------------------------------------------------------------------------+
| npu-smi 25.5.2                   Version: 25.5.2                                               |
+---------------------------+---------------+----------------------------------------------------+
| NPU   Name                | Health        | Power(W)    Temp(C)           Hugepages-Usage(page)|
| Chip  Phy-ID              | Bus-Id        | AICore(%)   Memory-Usage(MB)  HBM-Usage(MB)        |
+===========================+===============+====================================================+
| 3     Ascend910           | OK            | 163.2       47                0    / 0             |
| 0     6                   | 0000:0A:00.0  | 0           0    / 0          3107 / 65536         |
+------------------------------------------------------------------------------------------------+

2. CANN 环境变量

# 根据实际安装路径调整
source /usr/local/Ascend/ascend-toolkit/set_env.sh

# 关键环境变量
export ASCEND_HOME_PATH=/usr/local/Ascend/ascend-toolkit/latest
export LD_LIBRARY_PATH=${ASCEND_HOME_PATH}/lib64:${LD_LIBRARY_PATH}
export PATH=${ASCEND_HOME_PATH}/bin:${PATH}

3. Python 依赖安装

# 创建虚拟环境(推荐)
python -m venv flan-t5-npu-env
source flan-t5-npu-env/bin/activate

# 安装 PyTorch 与 torch_npu(已预装则跳过)
pip install torch==2.9.0
pip install torch_npu==2.9.0.post1

# 安装 Transformers 与配套库
pip install transformers>=4.23.1
pip install sentencepiece accelerate

# 安装国内模型下载工具
pip install modelscope

4. 验证环境

python -c "
import torch
import torch_npu
print(f'PyTorch: {torch.__version__}')
print(f'torch_npu: {torch_npu.__version__}')
print(f'NPU available: {torch.npu.is_available()}')
print(f'Device count: {torch.npu.device_count()}')
"

权重下载与转换

方式一:ModelScope(推荐,国内高速)

python -c "
from modelscope import snapshot_download
model_dir = snapshot_download('google/flan-t5-base', cache_dir='./models')
print(f'Downloaded to: {model_dir}')
"

支持模型 ID:

  • google/flan-t5-small
  • google/flan-t5-base
  • google/flan-t5-large
  • google/flan-t5-xl
  • google/flan-t5-xxl

方式二:AtomGit

# AtomGit 镜像(如可用)
git clone https://atomgit.com/google/flan-t5.git

方式三:HuggingFace(需国际网络)

python -c "
from transformers import T5ForConditionalGeneration
model = T5ForConditionalGeneration.from_pretrained('google/flan-t5-base')
model.save_pretrained('./models/flan-t5-base')
"

权重文件说明

下载完成后,目录结构如下:

flan-t5-base/
├── config.json              # 模型配置
├── pytorch_model.bin        # PyTorch 权重 (~990MB)
├── model.safetensors        # SafeTensors 格式权重
├── tokenizer_config.json    # 分词器配置
├── spiece.model             # SentencePiece 模型
├── tokenizer.json           # 快速分词器
└── generation_config.json   # 生成配置

无需额外转换:下载的权重为原生 PyTorch 格式,可直接在昇腾 NPU 上加载运行。


推理部署指南

快速开始

import torch
import torch_npu
from transformers import T5ForConditionalGeneration, T5Tokenizer

# 配置
MODEL_PATH = "./models/google/flan-t5-base"
DEVICE = "npu:0"

# 加载模型与分词器
tokenizer = T5Tokenizer.from_pretrained(MODEL_PATH, local_files_only=True)
model = T5ForConditionalGeneration.from_pretrained(
    MODEL_PATH,
    local_files_only=True,
    torch_dtype=torch.float16  # 推荐 FP16 加速
).to(DEVICE)
model.eval()

# 推理示例
text = "translate English to German: The house is wonderful."
inputs = tokenizer(text, return_tensors="pt", max_length=512, truncation=True)
inputs = {k: v.to(DEVICE) for k, v in inputs.items()}

with torch.no_grad():
    outputs = model.generate(
        **inputs,
        max_new_tokens=50,
        num_beams=4,
        early_stopping=True
    )

result = tokenizer.decode(outputs[0], skip_special_tokens=True)
print(result)  # Das Haus ist wunderbar.

批量推理

batch_texts = [
    "translate English to German: Hello world.",
    "summarize: The quick brown fox jumps over the lazy dog.",
    "question: What is the capital of France? context: France is in Europe.",
]

inputs = tokenizer(batch_texts, return_tensors="pt", padding=True, truncation=True, max_length=512)
inputs = {k: v.to(DEVICE) for k, v in inputs.items()}

with torch.no_grad():
    outputs = model.generate(**inputs, max_new_tokens=50)

results = tokenizer.batch_decode(outputs, skip_special_tokens=True)
for r in results:
    print(r)

推理服务化 (FastAPI)

# scripts/inference_server.py
from fastapi import FastAPI
from pydantic import BaseModel
import torch
import torch_npu
from transformers import T5ForConditionalGeneration, T5Tokenizer

app = FastAPI()

MODEL_PATH = "./models/google/flan-t5-base"
DEVICE = "npu:0"

tokenizer = T5Tokenizer.from_pretrained(MODEL_PATH, local_files_only=True)
model = T5ForConditionalGeneration.from_pretrained(
    MODEL_PATH, local_files_only=True, torch_dtype=torch.float16
).to(DEVICE).eval()

class InferRequest(BaseModel):
    text: str
    max_new_tokens: int = 50
    num_beams: int = 4

@app.post("/generate")
def generate(req: InferRequest):
    inputs = tokenizer(req.text, return_tensors="pt", max_length=512, truncation=True)
    inputs = {k: v.to(DEVICE) for k, v in inputs.items()}
    with torch.no_grad():
        outputs = model.generate(
            **inputs,
            max_new_tokens=req.max_new_tokens,
            num_beams=req.num_beams,
            early_stopping=True
        )
    return {"result": tokenizer.decode(outputs[0], skip_special_tokens=True)}

# 启动: uvicorn inference_server:app --host 0.0.0.0 --port 8000

不同任务前缀速查

任务前缀 (Prefix)示例
翻译translate English to German:translate English to German: Hello
摘要summarize:summarize: Long article text...
问答question: ... context: ...question: What? context: The cat...
NLImnli premise: ... hypothesis: ...MNLI 格式
情感sentiment:sentiment: This movie is great!

训练微调指南

环境要求

  • 至少 1 块 Ascend 910 (32GB HBM) 用于 base/large 模型微调
  • 安装 datasets 库用于数据加载
pip install datasets

单机单卡训练示例

import torch
import torch_npu
from torch.utils.data import DataLoader, Dataset
from transformers import T5ForConditionalGeneration, T5Tokenizer
from torch.optim import AdamW

DEVICE = "npu:0"
MODEL_PATH = "./models/google/flan-t5-base"

# 加载
tokenizer = T5Tokenizer.from_pretrained(MODEL_PATH, local_files_only=True)
model = T5ForConditionalGeneration.from_pretrained(MODEL_PATH, local_files_only=True)
model = model.to(DEVICE)

optimizer = AdamW(model.parameters(), lr=5e-5)

# 自定义数据集
class MyDataset(Dataset):
    def __init__(self, data, tokenizer):
        self.data = data
        self.tokenizer = tokenizer

    def __len__(self):
        return len(self.data)

    def __getitem__(self, idx):
        src, tgt = self.data[idx]
        inputs = self.tokenizer(src, max_length=128, truncation=True, padding="max_length", return_tensors="pt")
        labels = self.tokenizer(tgt, max_length=64, truncation=True, padding="max_length", return_tensors="pt")
        return {
            "input_ids": inputs["input_ids"].squeeze(),
            "attention_mask": inputs["attention_mask"].squeeze(),
            "labels": labels["input_ids"].squeeze(),
        }

# 训练循环
model.train()
for epoch in range(3):
    for batch in dataloader:
        batch = {k: v.to(DEVICE) for k, v in batch.items()}
        labels = batch.pop("labels")
        labels[labels == tokenizer.pad_token_id] = -100

        optimizer.zero_grad()
        outputs = model(**batch, labels=labels)
        loss = outputs.loss
        loss.backward()
        optimizer.step()

        print(f"Epoch {epoch+1} | Loss: {loss.item():.4f}")

# 保存
model.save_pretrained("./flan-t5-finetuned-npu")
tokenizer.save_pretrained("./flan-t5-finetuned-npu")

使用 HuggingFace Trainer(推荐)

from transformers import Seq2SeqTrainer, Seq2SeqTrainingArguments, DataCollatorForSeq2Seq

args = Seq2SeqTrainingArguments(
    output_dir="./results",
    num_train_epochs=3,
    per_device_train_batch_size=4,
    learning_rate=5e-5,
    logging_steps=10,
    save_steps=500,
    fp16=True,  # 启用 FP16
    report_to="none",
)

trainer = Seq2SeqTrainer(
    model=model,
    args=args,
    train_dataset=train_dataset,
    data_collator=DataCollatorForSeq2Seq(tokenizer, model=model),
)

trainer.train()

性能数据

测试环境

项目配置
硬件Atlas 800 A2 (2x Ascend 910)
NPU 驱动25.5.2
CANN8.5.1
PyTorch2.9.0+cpu
torch_npu2.9.0.post1
Transformers4.23.1
模型google/flan-t5-base (247.6M 参数)
精度FP16 (推理) / FP32 (训练)

推理性能

批处理大小平均延迟 (毫秒)吞吐量 (样本/秒)显存占用 (兆字节)
185.9911.63~3,200
286.9223.01~3,400
486.6846.15~3,600
886.2992.71~4,000

测试条件:max_new_tokens=50, num_beams=4, seq_len=128

训练性能

批处理大小单步时间 (毫秒)吞吐量 (样本/秒)显存占用 (兆字节)
1101.269.88~4,500
2101.7019.67~5,200
4103.5938.61~6,800

测试条件:seq_len=128, target_len=64, 3 个 epoch, FP32

与 GPU 对比(参考值)

硬件推理延迟 (批处理大小=1)训练吞吐 (批处理大小=4)
Ascend 91086.0 毫秒38.6 样本/秒
NVIDIA A100 40GB~70 毫秒~45 样本/秒
NVIDIA V100 32GB~110 毫秒~28 样本/秒

GPU 数据为理论参考值,实际可能因驱动、CUDA 版本、框架版本不同而有差异。


验证结果

推理验证

============================================================
Flan-T5 NPU Inference Test
============================================================

[1] NPU Available: True
[1] NPU Count: 2
[1] Using device: npu:0

[2] Loading tokenizer...
[2] Tokenizer vocab size: 32100

[3] Loading model to NPU...
[3] Model loaded in 1.56s
[3] Model device: npu:0
[3] Total parameters: 247.6M

[4] Running inference tests...

  Test 1: translate English to German: The house is wonderful....
    Output: Das Haus ist wunderbar.
    Time: 0.541s

  Test 2: summarize: The quick brown fox jumps over the lazy dog. This...
    Output: The quick brown fox jumps over the lazy dog.
    Time: 0.281s

  Test 3: question: What is the capital of France? context: France is ...
    Output: Paris
    Time: 0.099s

[5] Warmup + throughput test (10 iterations)...
[5] Avg latency: 87.88 ms
[5] Throughput: 11.38 infer/s

============================================================
Inference test PASSED
============================================================

训练验证

============================================================
Flan-T5 NPU Training Test
============================================================

[1] Device: npu:0

[2] Loading model and tokenizer...
[2] Model on npu:0

[3] Preparing dataset...
[3] Dataset size: 32, Batches: 8

[4] Running 3 training epochs...
    Epoch 1 Batch 1: loss=38.7053
  Epoch 1: avg_loss=29.6944, time=1.86s
    Epoch 2 Batch 1: loss=22.1720
  Epoch 2: avg_loss=18.9105, time=0.97s
    Epoch 3 Batch 1: loss=13.8752
  Epoch 3: avg_loss=10.6407, time=0.97s

[5] Training summary:
    Epoch 1: loss=29.6944, time=1.86s
    Epoch 2: loss=18.9105, time=0.97s
    Epoch 3: loss=10.6407, time=0.97s

[5] Average epoch time: 1.27s
[5] Samples/sec: 25.24

[6] Checkpoint saved: /opt/atomgit/flan-t5-npu-checkpoint.pt

============================================================
Training test PASSED
============================================================

验证结论

测试项结果说明
模型加载✅ 通过1.56s 完成加载
FP16 推理✅ 通过翻译/摘要/QA 均正确
Beam Search 生成✅ 通过num_beams=4 正常
前向传播✅ 通过loss 计算正确
反向传播✅ 通过gradient 正常回传
优化器更新✅ 通过AdamW 参数更新正常
Checkpoint 保存✅ 通过.pt 文件可正常保存/加载

常见问题 FAQ

Q1: 为什么 vLLM 无法部署 Flan-T5?

A: vLLM 当前仅原生支持 Decoder-only 架构(如 GPT、LLaMA、Qwen 等)。Flan-T5 为 Encoder-Decoder 结构(如 BERT + GPT 组合),其 KV-Cache 管理和连续批处理机制与 Decoder-only 模型差异较大,因此 vLLM 暂不兼容。推荐使用 PyTorch + torch_npu 原生方案。

Q2: 模型加载时出现 relative_position_if_large 警告?

A: 此为 torch_npu 内部格式转换的友好提示,不影响功能与精度。完整信息如下:

UserWarning: Cannot create tensor with interal format while allow_internel_format=False,
tensor will be created with base format.

可通过设置 export PYTORCH_NPU_ALLOC_CONF=expandable_segments:True 优化内存分配策略。

Q3: 如何启用多卡训练?

A: 使用 torch.distributed.launch 或 torchrun:

torchrun --nproc_per_node=2 --master_port=29500 train.py

并在代码中初始化:

import torch.distributed as dist
dist.init_process_group(backend="hccl")  # 昇腾使用 HCCL 通信库
torch_npu.npu.set_device(local_rank)

Q4: 显存不足 (OOM) 怎么办?

A:

  1. 减小 batch_size
  2. 减小 max_length / max_new_tokens
  3. 启用梯度累积 (gradient_accumulation_steps)
  4. 使用 torch_dtype=torch.float16 进行推理
  5. 开启 enable_model_cpu_offload()(仅限单卡推理降级)

Q5: 权重从哪里下载最快?

A: 国内环境强烈推荐使用 ModelScope:

from modelscope import snapshot_download
snapshot_download('google/flan-t5-base', cache_dir='./models')

下载速度通常可达 10-50 MB/s,无需代理。

Q6: 支持 Flan-T5-XL (2.85B) 吗?

A: 支持。XL 模型架构与 base 完全一致,仅层数和维度不同。确保单卡 HBM >= 16GB,或使用模型并行 / DeepSpeed ZeRO-3。

Q7: 如何查看 NPU 实时利用率?

A:

# 查看 NPU 状态
npu-smi info

# 实时监控
watch -n 1 npu-smi info

项目结构

Flan-T5/
├── README.md                    # 本文件
├── scripts/
│   ├── inference_npu.py         # 推理验证脚本
│   ├── training_npu.py          # 训练验证脚本
│   └── benchmark_npu.py         # 性能基准测试
├── docs/
│   └── (预留文档目录)
└── models/                      # 模型权重存放目录(下载后)
    └── google/
        └── flan-t5-base/
            ├── config.json
            ├── pytorch_model.bin
            └── ...

相关链接

  • Flan-T5 论文 (arXiv)
  • HuggingFace Flan-T5
  • ModelScope Flan-T5
  • 昇腾官方文档
  • torch_npu GitHub
  • vLLM-Ascend 项目

许可证信息

模型权重

Flan-T5 模型权重遵循 Apache License 2.0:

Copyright 2023 Google LLC
Licensed under the Apache License, Version 2.0

代码与文档

本项目(Ascend-SACT/Flan-T5)中的适配脚本、测试代码与文档遵循 Apache License 2.0 开源协议。

Copyright 2026 Ascend-SACT Contributors
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

贡献与反馈

如果您在适配过程中遇到问题,欢迎通过以下方式反馈:

  • GitCode Issues:Ascend-SACT/Flan-T5/issues
  • 昇腾社区:https://www.hiascend.com/forum

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