multimodal

Multi-Modal

This document shows how to run multimodal pipelines with TensorRT-LLM, e.g. from image+text input modalities to text output.

Multimodal models' LLM part has an additional parameter --max_multimodal_len compared to LLM-only build commands. Under the hood, max_multimodal_len and max_prompt_embedding_table_size are effectively the same concept, i.e., prepended/concatenated embeddings (either multimodal feature embeddings or prompt tuning embeddings) to the LLM input embeddings. The multimodal features from the visual encoder of shape [batch_size, num_visual_features, visual_hidden_dim] is flattened as [batch_size * num_visual_features, visual_hidden_dim] and passed like a prompt embedding table.

We first describe how to run each model on a single GPU. We then provide general guidelines on using tensor parallelism for LLM part of the pipeline.

BLIP2-T5

1. Download Huggingface weights and convert original checkpoint to TRT-LLM checkpoint format following example in examples/enc_dec/README.md.

   export MODEL_NAME=flan-t5-xl
   git clone https://huggingface.co/google/${MODEL_NAME} tmp/hf_models/${MODEL_NAME}
   
   python ../enc_dec/t5/convert.py -i tmp/hf_models/${MODEL_NAME} \
       -o tmp/trt_models/${MODEL_NAME} --weight_data_type float32 \
       --inference_tensor_para_size 1

2. Build TRT-LLM engine from TRT-LLM checkpoint

   python ../enc_dec/build.py --model_type t5 \
       --weight_dir tmp/trt_models/${MODEL_NAME}/tp1 \
       --output_dir trt_engines/${MODEL_NAME}/1-gpu \
       --engine_name ${MODEL_NAME} \
       --remove_input_padding \
       --use_bert_attention_plugin \
       --use_gpt_attention_plugin \
       --use_gemm_plugin \
       --dtype bfloat16 \
       --max_beam_width 1 \
       --max_batch_size 8 \
       --max_encoder_input_len 924 \
       --max_output_len 100 \
       --max_multimodal_len 256 # 8 (max_batch_size) * 32 (num_visual_features)

   NOTE: max_multimodal_len = max_batch_size * num_visual_features, so if you change max_batch_size, max multimodal length MUST be changed accordingly.

   The built T5 engines are located in ./trt_engines/${MODEL_NAME}/1-gpu/bfloat16/tp1.

3. Build TensorRT engines for visual components

   python build_visual_engine.py --model_name ${MODEL_NAME} --model_path tmp/hf_models/${MODEL_NAME} --max_batch_size 8

   The built engines are located in ./visual_engines/${MODEL_NAME}.

   To run the BLIP2 pipeline with batch size > 1, change --max_batch_size argument to build_visual_engine.py accordingly.

4. Assemble everything into BLIP2 pipeline

   python run.py \
       --blip2_encoder \
       --max_new_tokens 30 \
       --input_text "Question: which city is this? Answer:" \
       --hf_model_dir tmp/hf_models/${MODEL_NAME} \
       --visual_engine_dir visual_engines/${MODEL_NAME} \
       --llm_engine_dir trt_engines/${MODEL_NAME}/1-gpu/bfloat16/tp1

BLIP2-OPT

OPT pipeline needs few minor changes from T5 pipeline

1. Convert Huggingface weights to TRT-LLM checkpoint format following examples/opt/README.md.

2. Use trtllm-build command to build TRT-LLM engine for OPT.

3. Add --decoder-llm argument to inference script, since OPT is a decoder-only LLM.

4. The full list of commands is as follows:

   export MODEL_NAME=opt-2.7b
   git clone https://huggingface.co/facebook/${MODEL_NAME} tmp/hf_models/${MODEL_NAME}
   
   python ../opt/convert_checkpoint.py \
       --model_dir tmp/hf_models/${MODEL_NAME} \
       --dtype float16 \
       --output_dir tmp/trt_models/${MODEL_NAME}/fp16/1-gpu
   
   trtllm-build \
       --checkpoint_dir tmp/trt_models/${MODEL_NAME}/fp16/1-gpu \
       --output_dir trt_engines/${MODEL_NAME}/fp16/1-gpu \
       --gemm_plugin float16 \
       --max_beam_width 1 \
       --max_batch_size 8 \
       --max_multimodal_len 256 \
       --max_input_len 924 \
       --max_output_len 100
   
   python build_visual_engine.py --model_name ${MODEL_NAME} --model_path tmp/hf_models/${MODEL_NAME}
   
   python run.py \
       --blip2_encoder \
       --max_new_tokens 30 \
       --input_text "Question: which city is this? Answer:" \
       --hf_model_dir tmp/hf_models/${MODEL_NAME} \
       --visual_engine_dir visual_engines/${MODEL_NAME} \
       --llm_engine_dir trt_engines/${MODEL_NAME}/fp16/1-gpu \
       --decoder_llm

5. INT8/INT4 weight-only quantization for OPT can be enabled using commands as follows (take INT4 as an example, while INT8 is the default precision for weight-only quantization):

   python ../opt/convert_checkpoint.py \
       --model_dir tmp/hf_models/${MODEL_NAME} \
       --dtype float16 \
       --output_dir tmp/trt_models/${MODEL_NAME}/int4_weightonly/1-gpu \
       --use_weight_only \
       --weight_only_precision int4
   
   trtllm-build \
       --checkpoint_dir tmp/trt_models/${MODEL_NAME}/int4_weightonly/1-gpu \
       --output_dir trt_engines/${MODEL_NAME}/int4_weightonly/1-gpu \
       --gemm_plugin float16 \
       --max_beam_width 1 \
       --max_batch_size 8 \
       --max_multimodal_len 256 \
       --max_input_len 924 \
       --max_output_len 100

   The built OPT engines lie in trt_engines/${MODEL_NAME}/int4_weightonly/1-gpu. You should use this directory as --llm_engine_dir argument to run.py

   NOTE: INT8/INT4 option is not supported for BLIP2-T5, because quantization support has not been added for encoder-decoder models yet.

LLaVA

1. Download Huggingface model weights. This model has both LLM and visual components unlike BLIP2 example which downloads only LLM components from Huggingface.

   export MODEL_NAME="llava-1.5-7b-hf"
   git clone https://huggingface.co/llava-hf/${MODEL_NAME} tmp/hf_models/${MODEL_NAME}

2. Generate TRT-LLM engine for LLaMA following example in examples/llama/README.md

   python ../llama/convert_checkpoint.py \
       --model_dir tmp/hf_models/${MODEL_NAME} \
       --output_dir tmp/trt_models/${MODEL_NAME}/fp16/1-gpu \
       --dtype float16
   
   trtllm-build \
       --checkpoint_dir tmp/trt_models/${MODEL_NAME}/fp16/1-gpu \
       --output_dir trt_engines/${MODEL_NAME}/fp16/1-gpu \
       --gemm_plugin float16 \
       --max_batch_size 1 \
       --max_input_len 2048 \
       --max_output_len 512 \
       --max_multimodal_len 576 # 1 (max_batch_size) * 576 (num_visual_features)

3. Build TensorRT engines for visual components

   python build_visual_engine.py --model_name ${MODEL_NAME} --model_path tmp/hf_models/${MODEL_NAME}

4. Add --decoder-llm argument to inference script, since LLaMA is a decoder-only LLM.

   python run.py \
       --max_new_tokens 30 \
       --input_text "Question: which city is this? Answer:" \
       --hf_model_dir tmp/hf_models/${MODEL_NAME} \
       --visual_engine_dir visual_engines/${MODEL_NAME} \
       --llm_engine_dir trt_engines/${MODEL_NAME}/fp16/1-gpu \
       --decoder_llm

5. INT8/INT4 weight-only quantization for LLaMA can be enabled as follows (take INT4 as an example, while INT8 is the default precision for weight-only quantization):

   python ../llama/convert_checkpoint.py \
       --model_dir tmp/hf_models/${MODEL_NAME} \
       --dtype float16 \
       --output_dir tmp/trt_models/${MODEL_NAME}/int4_weightonly/1-gpu \
       --use_weight_only \
       --weight_only_precision int4
   
   trtllm-build \
       --checkpoint_dir tmp/trt_models/${MODEL_NAME}/int4_weightonly/1-gpu \
       --output_dir trt_engines/${MODEL_NAME}/int4_weightonly/1-gpu \
       --gemm_plugin float16 \
       --max_batch_size 1 \
       --max_input_len 924 \
       --max_output_len 100 \
       --max_multimodal_len 576

   The built engines lie in trt_engines/${MODEL_NAME}/int4_weightonly/1-gpu. You should use this directory as --llm_engine_dir argument to run.py

6. One can use LLaVA with other quantization options, like SmoothQuant and INT4 AWQ, that are supported by LLaMA. Instructions in ../llama/README.md to enable SmoothQuant and INT4 AWQ can be re-used to generate quantized TRT engines for LLM component of LLaVA.

Nougat

1. Download Huggingface weights

   export MODEL_NAME="nougat-base" # or nougat-small
   git clone https://huggingface.co/facebook/${MODEL_NAME} tmp/hf_models/${MODEL_NAME}

2. Convert Huggingface weights into TRT-LLM checkpoints and build TRT engines using scripts in examples/enc_dec

   Nougat uses mBART architecture but replaces the LLM encoder with a Swin Transformer encoder. To achieve this, we add an extra --nougat flag (over mBART example) to bart/convert.py and build.py in examples/enc_dec.

   python ../enc_dec/bart/convert.py -i tmp/hf_models/${MODEL_NAME} \
       -o tmp/trt_models/${MODEL_NAME} --weight_data_type float32 \
       --inference_tensor_para_size 1 --nougat
   
   python ../enc_dec/build.py \
       --model_type bart \
       --weight_dir tmp/trt_models/${MODEL_NAME}/tp1 \
       -o trt_engines/${MODEL_NAME}/1-gpu \
       --engine_name $MODEL_NAME \
       --bert_attention_plugin \
       --use_gpt_attention_plugin \
       --use_gemm_plugin \
       --dtype bfloat16 \
       --max_beam_width 1 \
       --max_batch_size 1 \
       --nougat \
       --max_output_len 100 \
       --max_multimodal_len 588 # 1 (max_batch_size) * 588 (num_visual_features)

3. Generate TensorRT engines for visual components and combine everything into final pipeline.

   python build_visual_engine.py --model_name ${MODEL_NAME} --model_path tmp/hf_models/${MODEL_NAME}
   
   python run.py \
       --hf_model_dir tmp/hf_models/${MODEL_NAME} \
       --visual_engine_dir visual_engines/${MODEL_NAME} \
       --llm_engine_dir trt_engines/${MODEL_NAME}/1-gpu/bfloat16/tp1 \
       --nougat

Enabling tensor parallelism for multi-GPU

The LLM part of the pipeline can be run on multiple GPUs using tensor parallelism. The visual encoder will be replicated on each GPU and operate in a data parallel fashion.

To enable tensor parallelism, both weight conversion step (from Huggingface to FT format) and engine building step should use additional arguments. Finally run.py should be prefixed with mpirun -n NUM_GPUS --allow-run-as-root.

The full set of commands to enable 2-way tensor parallelism for LLaVA is:

```bash
export MODEL_NAME="llava-1.5-7b-hf"

python ../llama/convert_checkpoint.py \
    --model_dir tmp/hf_models/${MODEL_NAME} \
    --output_dir tmp/trt_models/${MODEL_NAME}/fp16/2-gpu \
    --dtype float16 --tp_size 2

trtllm-build \
    --checkpoint_dir tmp/trt_models/${MODEL_NAME}/fp16/2-gpu \
    --output_dir trt_engines/${MODEL_NAME}/fp16/2-gpu \
    --gemm_plugin float16 \
    --max_batch_size 1 \
    --max_input_len 2048 \
    --max_output_len 512 \
    --max_multimodal_len 576

python build_visual_engine.py --model_name ${MODEL_NAME} --model_path tmp/hf_models/${MODEL_NAME}

mpirun -n 2 --allow-run-as-root \
    python run.py \
    --max_new_tokens 30 \
    --hf_model_dir tmp/hf_models/${MODEL_NAME} \
    --visual_engine_dir visual_engines/${MODEL_NAME} \
    --llm_engine_dir trt_engines/${MODEL_NAME}/fp16/2-gpu \
    --decoder_llm
```