bloom

BLOOM

This document shows how to build and run a BLOOM model in TensorRT-LLM on both single GPU, single node multi-GPU and multi-node multi-GPU.

Table of Contents

• BLOOM
  • Table of Contents
  • Overview
  • Support Matrix
  • Usage
    • Build TensorRT engine(s)
      • INT8 weight only + INT8 KV cache
      • SmoothQuant
    • 4. Run

Overview

The TensorRT-LLM BLOOM implementation can be found in tensorrt_llm/models/bloom/model.py. The TensorRT-LLM BLOOM example code is located in examples/bloom. There is one main file:

• convert_checkpoint.py to convert a checkpoint from the HuggingFace (HF) Transformers format to the TensorRT-LLM format

In addition, there are two shared files in the parent folder examples for inference and evaluation:

• ../run.py to run the inference on an input text;
• ../summarize.py to summarize the articles in the cnn_dailymail dataset.

Support Matrix

• FP16
• INT8 & INT4 Weight-Only
• INT8 KV CACHE
• Smooth Quant
• Tensor Parallel

Usage

The TensorRT-LLM BLOOM example code locates at examples/bloom. It takes HF weights as input, and builds the corresponding TensorRT engines. The number of TensorRT engines depends on the number of GPUs used to run inference.

Build TensorRT engine(s)

Please install required packages first:

pip install -r requirements.txt

Need to prepare the HF BLOOM checkpoint by following the guides here https://huggingface.co/docs/transformers/main/en/model_doc/bloom.

e.g. To install BLOOM-560M

# Setup git-lfs
git lfs install
rm -rf ./bloom/560M
mkdir -p ./bloom/560M && git clone https://huggingface.co/bigscience/bloom-560m ./bloom/560M

TensorRT-LLM BLOOM builds TensorRT engine(s) from HF checkpoint. If no checkpoint directory is specified, TensorRT-LLM will build engine(s) with dummy weights.

Normally trtllm-build only requires single GPU, but if you've already got all the GPUs needed for inference, you could enable parallel building to make the engine building process faster by adding --workers argument. Please note that currently workers feature only supports single node.

Here're some examples:

# Build a single-GPU float16 engine from HF weights.
# Try gemm_plugin to prevent accuracy issue. TODO check this holds for BLOOM

# Single GPU on BLOOM 560M
python convert_checkpoint.py --model_dir ./bloom/560M/ \
                --dtype float16 \
                --output_dir ./bloom/560M/trt_ckpt/fp16/1-gpu/
trtllm-build --checkpoint_dir ./bloom/560M/trt_ckpt/fp16/1-gpu/ \
                --gemm_plugin float16 \
                --output_dir ./bloom/560M/trt_engines/fp16/1-gpu/

# Build the BLOOM 560M using a single GPU and apply INT8 weight-only quantization.
python convert_checkpoint.py --model_dir ./bloom/560M/ \
                --dtype float16 \
                --use_weight_only \
                --output_dir ./bloom/560M/trt_ckpt/int8_weight_only/1-gpu/
trtllm-build --checkpoint_dir ./bloom/560M/trt_ckpt/int8_weight_only/1-gpu/ \
                --gemm_plugin float16 \
                --output_dir ./bloom/560M/trt_engines/int8_weight_only/1-gpu/

# Use 2-way tensor parallelism on BLOOM 560M
python convert_checkpoint.py --model_dir ./bloom/560M/ \
                --dtype float16 \
                --output_dir ./bloom/560M/trt_ckpt/fp16/2-gpu/ \
                --tp_size 2
trtllm-build --checkpoint_dir ./bloom/560M/trt_ckpt/fp16/2-gpu/ \
                --gemm_plugin float16 \
                --output_dir ./bloom/560M/trt_engines/fp16/2-gpu/

# Use 8-way tensor parallelism on BLOOM 176B
# Currently, TensorRT does not support tensors with more than 2^31-1 elements,
# so we have to shard the embedding table to multi-GPUs.

# sharding embedding table in the vocab dimension (the lookup plugin is optional)
python convert_checkpoint.py --model_dir ./bloom/176B/ \
                --dtype float16 \
                --output_dir ./bloom/176B/trt_ckpt/fp16/8-gpu/ \
                --tp_size 8 \
                --use_parallel_embedding \
                --embedding_sharding_dim 0
trtllm-build --checkpoint_dir ./bloom/176B/trt_ckpt/fp16/8-gpu/ \
                --gemm_plugin float16 \
                --lookup_plugin float16 \
                --output_dir ./bloom/176B/trt_engines/fp16/8-gpu/ \
                --workers 2

# sharding embedding table in the hidden dimension
python convert_checkpoint.py --model_dir ./bloom/176B/ \
                --dtype float16 \
                --output_dir ./bloom/176B/trt_ckpt/fp16/8-gpu/ \
                --tp_size 8 \
                --use_parallel_embedding \
                --embedding_sharding_dim 1
trtllm-build --checkpoint_dir ./bloom/176B/trt_ckpt/fp16/8-gpu/ \
                --gemm_plugin float16 \
                --output_dir ./bloom/176B/trt_engines/fp16/8-gpu/ \
                --workers 2

# share embedding table between embedding() and lm_head() layers
# To reduce the generated engine size, we has to use gemm and lookup plugin (--use_gemm_plugin --use_lookup_plugin) and must shard the embedding table in the vocab dimension.
python convert_checkpoint.py --model_dir ./bloom/176B/ \
                --dtype float16 \
                --output_dir ./bloom/176B/trt_ckpt/fp16/8-gpu/ \
                --tp_size 8 \
                --use_parallel_embedding \
                --embedding_sharding_dim 0 \
                --use_embedding_sharing
trtllm-build --checkpoint_dir ./bloom/176B/trt_ckpt/fp16/8-gpu/ \
                --gemm_plugin float16 \
                --lookup_plugin float16 \
                --output_dir ./bloom/176B/trt_engines/fp16/8-gpu/ \
                --workers 2

INT8 weight only + INT8 KV cache

For INT8 KV cache, convert_checkpoint.py add new options for the support of INT8 KV cache.

--int8_kv_cache is the command-line option to enable INT8 KV cache.

In addition, it could be combined with INT8 weight-only quantization, as follows:

Examples of INT8 weight-only quantization + INT8 KV cache

# Build model with both INT8 weight-only and INT8 KV cache enabled
python convert_checkpoint.py --model_dir ./bloom/560m/ \
                --dtype float16 \
                --int8_kv_cache \
                --use_weight_only --output_dir ./bloom/560m/trt_ckpt/int8/1-gpu/
trtllm-build --checkpoint_dir ./bloom/560m/trt_ckpt/int8/1-gpu/ \
                --gemm_plugin float16 \
                --output_dir ./bloom/560m/trt_engines/int8/1-gpu/ \
                --strongly_typed

SmoothQuant

Unlike the FP16 build where the HF weights are processed and loaded into the TensorRT-LLM directly, the SmoothQuant needs to load INT8 weights which should be pre-processed before building an engine.

Example:

python convert_checkpoint.py --model_dir bloom/560M/  --output_dir tllm_checkpoint_1gpu --smoothquant 0.5 --per_token --per_channel

convert_checkpoint.py add new options for the support of INT8 inference of SmoothQuant models.

--smoothquant is the starting point of INT8 inference. By default, it will run the model in the per-tensor mode.

Then, you can add any combination of --per-token and --per-channel to get the corresponding behaviors.

# Build model for SmoothQuant with below command.

trtllm-build  --checkpoint_dir tllm_checkpoint_1gpu  --output_dir ./engine_outputs

Note that GPT attention plugin is required to be enabled for SmoothQuant for now.

Note we use --bin_model_dir instead of --model_dir since SmoothQuant model needs INT8 weights and various scales from the binary files.

4. Run

python ../summarize.py --test_trt_llm \
                       --hf_model_dir ./bloom/560M/ \
                       --data_type fp16 \
                       --engine_dir ./bloom/560M/trt_engines/fp16/1-gpu/

python ../summarize.py --test_trt_llm \
                       --hf_model_dir ./bloom/560M/ \
                       --data_type fp16 \
                       --engine_dir ./bloom/560M/trt_engines/int8_weight_only/1-gpu/

mpirun -n 2 --allow-run-as-root \
    python ../summarize.py --test_trt_llm \
                           --hf_model_dir ./bloom/560M/ \
                           --data_type fp16 \
                           --engine_dir ./bloom/560M/trt_engines/fp16/2-gpu/

mpirun -n 8 --allow-run-as-root \
    python ../summarize.py --test_trt_llm \
                           --hf_model_dir ./bloom/176B/ \
                           --data_type fp16 \
                           --engine_dir ./bloom/176B/trt_engines/fp16/8-gpu/