Official PyTorch implementation for Extreme Compression of Large Language Models via Additive Quantization

[2024.05] AQLM was accepted to ICML'2024! If you're attending, meet us around this poster.

[2024.06] We released a new paper that extends AQLM with new finetuning algorithm called PV-tuning. We're also releasing PV-tuned AQLM models in this collection

[2024.08] We have merged the PV-Tuning branch into the main branch. To reproduce results with old finetuning (before Aug 21), use commit 559a366.

Learn how to run the prequantized models using this Google Colab examples:

Basic AQLM generation	Streaming with GPU/CPU	Inference with CUDA graphs (3x speedup)	Fine-tuning with PEFT	Serving with vLLM

This repository is currently designed to work with models of LLaMA, Mistral and Mixtral families. The models reported below use full model fine-tuning as described in appendix A, with cross-entropy objective with teacher logits.

We provide a number of prequantized AQLM models without PV-Tuning (scroll down for PV-Tuned models):

You can also download AQLM models tuned via PV-tuning:

Note that models with "g16" in their scheme require aqlm inference library v1.1.6 or newer:

pip install aqlm[gpu,cpu]>=1.1.6

Above perplexity is evaluated on 4k context length for Llama 2 models and 8k for Mistral/Mixtral and Llama 3. Please also note that token-level perplexity can only be compared within the same model family, but should not be compared between models that use different vocabularies. While Mistral has a lower perplexity than Llama 3 8B but this does not mean that Mistral is better: Llama's perplexity is computed on a much larger dictionary and has higher per-token perplexity because of that.

For more evaluation results and detailed explanations, please see our papers: Egiazarian et al. (2024) for pure AQLM and Malinovskii et al. (2024) for PV-Tuned models.

AQLM quantization setpus vary mainly on the number of codebooks used as well as the codebook sizes in bits. The most popular setups, as well as inference kernels they support are:

To run the models, one would have to install an inference library:

pip install aqlm[gpu,cpu]

, specifying either gpu, cpu or both based on one's inference setting.

Then, one can use the familiar .from_pretrained method provided by the transformers library:

from transformers import AutoModelForCausalLM

quantized_model = AutoModelForCausalLM.from_pretrained(
    "ISTA-DASLab/Llama-2-7b-AQLM-2Bit-1x16-hf",
    trust_remote_code=True, torch_dtype="auto"
).cuda()

Notice that torch_dtype should be set to either torch.float16 or "auto" on GPU and torch.float32 on CPU. After that, the model can be used exactly the same as one would use and unquantized model.

Install packages from requirements.txt:

pip install -r requirements.txt

The script will require downloading and caching locally the relevant tokenizer and the datasets. They will be saved in default Huggingface Datasets directory unless alternative location is provided by env variables. See relevant Datasets documentation section

When quantizing models with AQLM, we recommend that you use a subset of the original data the model was trained on.

For Llama-2 models, the closest available dataset is RedPajama . To load subset of RedPajama provide "pajama" in --dataset argument. This will process nsamples data and tokenize it using provided model tokenizer.

Additionally we provide tokenized Redpajama for LLama and Solar/Mistral models for 4096 context lengths stored in Hunggingface . To load it, use:

from huggingface_hub import hf_hub_download

hf_hub_download(repo_id="Vahe1994/AQLM", filename="data/name.pth", repo_type="dataset")

To use downloaded data from HF, place it in data folder(optional) and set correct path to it in "--dataset" argument in main.py.

Warning: These subsets are already processed with the corresponding model tokenizer. If you want to quantize another model (e.g. mistral/mixtral), please re-tokenize the data with provided script in src/datautils.

One can optionally log the data to Weights and Biases service (wandb). Run pip install wandb for W&B logging. Specify $WANDB_ENTITY, $WANDB_PROJECT, $WANDB_NAME environment variables prior to running experiments. use --wandb argument to enable logging

This code was developed and tested using a several A100 GPU with 80GB GPU RAM. You can use the --offload activations option to reduce VRAM usage. For Language Model Evaluation Harness evaluation one needs to have enough memory to load whole model activation tensors on one or several devices.

AQLM quantization takes considerably longer to calibrate than simpler quantization methods such as GPTQ. This only impacts quantization time, not inference time.

For instance, quantizing a 7B model with default configuration takes about 1 day on a single A100 gpu. Similarly, quantizing a 70B model on a single GPU would take 10-14 days. If you have multiple GPUs with fast interconnect, you can run AQLM multi-gpu to speed up comparison - simply set CUDA_VISIBLE_DEVICES for multiple GPUs. Quantizing 7B model on two gpus reduces quantization time to ~14.5 hours. Similarly, quantizing a 70B model on 8 x A100 GPUs takes 3 days 18 hours.

If you need to speed up quantization without adding more GPUs, you may also increase --relative_mse_tolerance or set --init_max_points_per_centroid or limit --finetune_max_epochs. However, that usually comes at a cost of reduced model accuracy.

The code requires the LLaMA model to be downloaded in Huggingface format and saved locally. The scripts below assume that $TRANSFORMERS_CACHE variable points to the Huggingface Transformers cache folder. To download and cache the models, run this in the same environment:

from transformers import AutoTokenizer, AutoModelForCausalLM
model_name = "meta-llama/Llama-2-7b-hf"  # or whatever else you wish to download
tokenizer = AutoTokenizer.from_pretrained(model_name, torch_dtype="auto")
model = AutoModelForCausalLM.from_pretrained(model_name, torch_dtype="auto")

This script compresses the model and then tests its performance in terms of perplexity using WikiText2, C4, and Penn Treebank datasets.

The command to launch the script should look like this:

export CUDA_VISIBLE_DEVICES=0   # or e.g. 0,1,2,3
export MODEL_PATH=<PATH_TO_MODEL_ON_HUB>
export DATASET_PATH=<INSERT DATASET NAME OR PATH TO CUSTOM DATA>
export SAVE_PATH=/path/to/save/quantized/model/
export WANDB_PROJECT=MY_AQ_EXPS
export WANDB_NAME=COOL_EXP_NAME

python main.py $MODEL_PATH $DATASET_PATH \
 --nsamples=1024 \
 --val_size=128 \
 --num_codebooks=1 \
 --nbits_per_codebook=16 \
 --in_group_size=8 \
 --relative_mse_tolerance=0.01 \
 --finetune_batch_size=32 \
 --finetune_max_epochs=10 \
 --finetune_early_stop=3 \
 --finetune_keep_best \
 --local_batch_size=1 \
 --offload_activations \
 --wandb \
 --resume \
 --save $SAVE_PATH

Main CLI arguments:

• CUDA_VISIBLE_DEVICES - by default, the code will use all available GPUs. If you want to use specific GPUs (or one GPU), use this variable.
• MODEL_PATH - a path to either Hugging Face hub (e.g. meta-llama/Llama-2-7b-hf) or a local folder with transformers model and a tokenizer.
• DATASET_PATH - either a path to calibration data (see above) or a standard dataset [c4, ptb, wikitext2]
  • for llama-2 models, you can use DATASET_PATH=./data/red_pajama_n=1024_4096_context_length.pth for a slice of RedPajama (up to 1024 samples)
• --nsamples - the number of calibration data sequences (train validation). If this parameter is not set, take all calibration data avaialble.
• --val_size - the number of validation sequences for early stopping on block finetuning. By default equal to 0. Must be smaller than --nsamples.
• --num_codebooks - number of codebooks per layer
• --nbits_per_codebook - each codebook will contain 2 ** nbits_per_codebook vectors
• --in_group_size - how many weights are quantized together (aka "g" in the arXiv paper)
• --finetune_batch_size - (for fine-tuning only) the total number of sequences used for each optimization step
• --local_batch_size - when accumulating finetune_batch_size, process this many samples per GPU per forward pass (affects GPU RAM usage)
• --relative_mse_tolerance- (for initial calibration) - stop training when (current_epoch_mse / previous_epoch_mse) > (1 - relative_mse_tolerance)
• --finetune_max_epochs - maximal number of passes through calibration data on block tuning.
• --finetune_early_stop - maximal number of passes through calibration data without improvement on validation.
• --offload_activations -- during calibration, move activations from GPU memory to RAM. This reduces VRAM usage while slowing calibration by ~10% (depending on your hardware).
• --save -- path to save/load quantized model. (see also: --load)
• --wandb - if this parameter is set, the code will log results to wandb
• --attn_implementation - specify attention (for transformers >= 4.38). Sdpa attention sometimes causes issues and it is recommended to use eager implementation.

There are additional hyperparameters aviailable. Run python main.py --help for more details on command line arguments, including compression parameters.

Note to reproduce results with old finetuning (before Aug 21), use commit 559a366. Old version of finetuning produced worse results than new one even without PV-tuning, but was faster.

The accuracy of the quantized model can be further improved via finetuning.

To use our new PV-Tuning algorithm, the command to launch the script should look like this:

torchrun --nproc-per-node=$NUM_GPUS finetune.py \
    --base_model $MODEL_PATH \
    --quantized_model $QUANTIZED_WEIGHTS_PATH \
    --model_seqlen=$SEQLEN \
    --block_type LlamaDecoderLayer \
    --load_dtype bfloat16 \
    --amp_dtype bfloat16 \
    --code_dtype uint16 \
    --dataset_name=pajama \
    --split none \
    --seed 42 \
    --preprocessing_chunk_length 100000 \
    --cache_dir=$CACHE_DIR \
    --trust_remote_code \
    --update_codes \
    --update_codebooks_and_scales \
    --update_non_quantized_parameters \
    --lamb \
    --debias \
    --lr 3e-4 \
    --adam_beta1 0.90 \
    --adam_beta2 0.95 \
    --max_code_change_per_step 1e-2 \
    --code_lr 1e-2 \
    --code_beta1 0.0 \
    --code_beta2 0.95 \
    --beam_size 5 \
    --delta_decay 0 \
    --batch_size=128 \
    --microbatch_size=1 \
    --max_epochs 1 \
    --gradient_checkpointing \
    --print_every_steps=1 \
    --verbose_optimizer \
    --wandb \
    --eval_every_steps=10 \
    --keep_best_model \
    --save $SAVE_PATH \
    --save_every_steps 100 \
    --attn_implementation flash_attention_2

To perform zero-shot evaluation, we adopt Language Model Evaluation Harness framework. Our code works with models in standard transformers`` format and may (optionally) load the weights of a quantized model via --aqlm_checkpoint_path` argument.

The evalution results in PV-Tuning were produced with lm-eval=0.4.0.

To run evaluation make sure that proper version is installed or install it via: pip install lm-eval==0.4.0.

The main script for launching the evaluation procedure is lmeval.py.

export CUDA_VISIBLE_DEVICES=0,1,2,3  # optional: select GPUs
export QUANTIZED_MODEL=<PATH_TO_SAVED_QUANTIZED_MODEL_FROM_MAIN.py>
export MODEL_PATH=<INSERT_PATH_TO_ORIINAL_MODEL_ON_HUB>
export DATASET=<INSERT DATASET NAME OR PATH TO CUSTOM DATA>
export WANDB_PROJECT=MY_AQLM_EVAL
export WANDB_NAME=COOL_EVAL_NAME

# for 0-shot evals
python lmeval.py \
    --model hf \
    --model_args pretrained=$MODEL_PATH,dtype=float16,parallelize=True \
    --tasks winogrande,piqa,hellaswag,arc_easy,arc_challenge \
    --batch_size <EVAL_BATCH_SIZE> \
    --aqlm_checkpoint_path QUANTIZED_MODEL # if evaluating quantized model

# for 5-shot MMLU
python lmeval.py \
    --model hf \
    --model_args pretrained=$MODEL_PATH,dtype=float16,parallelize=True \
    --tasks mmlu \
    --batch_size <EVAL_BATCH_SIZE> \
    --num_fewshot 5 \
    --aqlm_checkpoint_path QUANTIZED_MODEL # if evaluating quantized model

To convert a model into a Hugging Face compatible format, use convert_to_hf.py model in_path out_path with corresponding arguments:

• model - the original pretrained model (corresponds to MODEL_PATH of main.py, e.g. meta-llama/Llama-2-7b-hf).
• in_path - the folder containing an initially quantized model (corresponds to --save of main.py).
• out_path - the folder to save transformers model to.

You may also specify flags such as --save_safetensors to control the saved model format (see --help for details).

Example command: python convert_to_hf.py meta-llama/Llama-2-7b-hf ./path/to/saved/quantization ./converted-llama2-7b-hf --save_safetensors

Instructions for QuIP# finetuning can be found here.

If you want to contribute something substantial (more than a typo), please open an issue first. We use black and isort for all pull requests. Before committing your code run black . && isort .

If you found this work useful, please consider citing:

@misc{egiazarian2024extreme,
      title={Extreme Compression of Large Language Models via Additive Quantization}, 
      author={Vage Egiazarian and Andrei Panferov and Denis Kuznedelev and Elias Frantar and Artem Babenko and Dan Alistarh},
      year={2024},
      eprint={2401.06118},
      archivePrefix={arXiv},
      primaryClass={cs.LG}
}
@misc{malinovskii2024pvtuning,
      title={PV-Tuning: Beyond Straight-Through Estimation for Extreme LLM Compression}, 
      author={Vladimir Malinovskii and Denis Mazur and Ivan Ilin and Denis Kuznedelev and Konstantin Burlachenko and Kai Yi and Dan Alistarh and Peter Richtarik},
      year={2024},
      eprint={2405.14852},
      archivePrefix={arXiv},
      primaryClass={cs.LG}
}