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AWQ

Try AWQ quantization with this notebook!

Activation-aware Weight Quantization (AWQ) doesn’t quantize all the weights in a model, and instead, it preserves a small percentage of weights that are important for LLM performance. This significantly reduces quantization loss such that you can run models in 4-bit precision without experiencing any performance degradation.

There are several libraries for quantizing models with the AWQ algorithm, such as llm-awq, autoawq or optimum-intel. Transformers supports loading models quantized with the llm-awq and autoawq libraries. This guide will show you how to load models quantized with autoawq, but the process is similar for llm-awq quantized models.

Make sure you have autoawq installed:

pip install autoawq

AWQ-quantized models can be identified by checking the quantization_config attribute in the model’s config.json file:

{
  "_name_or_path": "/workspace/process/huggingfaceh4_zephyr-7b-alpha/source",
  "architectures": [
    "MistralForCausalLM"
  ],
  ...
  ...
  ...
  "quantization_config": {
    "quant_method": "awq",
    "zero_point": true,
    "group_size": 128,
    "bits": 4,
    "version": "gemm"
  }
}

A quantized model is loaded with the from_pretrained() method. If you loaded your model on the CPU, make sure to move it to a GPU device first. Use the device_map parameter to specify where to place the model:

from transformers import AutoModelForCausalLM, AutoTokenizer

model_id = "TheBloke/zephyr-7B-alpha-AWQ"
model = AutoModelForCausalLM.from_pretrained(model_id, device_map="cuda:0")

Loading an AWQ-quantized model automatically sets other weights to fp16 by default for performance reasons. If you want to load these other weights in a different format, use the torch_dtype parameter:

from transformers import AutoModelForCausalLM, AutoTokenizer

model_id = "TheBloke/zephyr-7B-alpha-AWQ"
model = AutoModelForCausalLM.from_pretrained(model_id, torch_dtype=torch.float32)

AWQ quantization can also be combined with FlashAttention-2 to further accelerate inference:

from transformers import AutoModelForCausalLM, AutoTokenizer

model = AutoModelForCausalLM.from_pretrained("TheBloke/zephyr-7B-alpha-AWQ", attn_implementation="flash_attention_2", device_map="cuda:0")

Fused modules

Fused modules offers improved accuracy and performance and it is supported out-of-the-box for AWQ modules for Llama and Mistral architectures, but you can also fuse AWQ modules for unsupported architectures.

Fused modules cannot be combined with other optimization techniques such as FlashAttention-2.

supported architectures

unsupported architectures

To enable fused modules for supported architectures, create an AwqConfig and set the parameters fuse_max_seq_len and do_fuse=True. The fuse_max_seq_len parameter is the total sequence length and it should include the context length and the expected generation length. You can set it to a larger value to be safe.

For example, to fuse the AWQ modules of the TheBloke/Mistral-7B-OpenOrca-AWQ model.

import torch
from transformers import AwqConfig, AutoModelForCausalLM

model_id = "TheBloke/Mistral-7B-OpenOrca-AWQ"

quantization_config = AwqConfig(
    bits=4,
    fuse_max_seq_len=512,
    do_fuse=True,
)

model = AutoModelForCausalLM.from_pretrained(model_id, quantization_config=quantization_config).to(0)

The TheBloke/Mistral-7B-OpenOrca-AWQ model was benchmarked with batch_size=1 with and without fused modules.

Unfused module

Batch Size	Prefill Length	Decode Length	Prefill tokens/s	Decode tokens/s	Memory (VRAM)
1	32	32	60.0984	38.4537	4.50 GB (5.68%)
1	64	64	1333.67	31.6604	4.50 GB (5.68%)
1	128	128	2434.06	31.6272	4.50 GB (5.68%)
1	256	256	3072.26	38.1731	4.50 GB (5.68%)
1	512	512	3184.74	31.6819	4.59 GB (5.80%)
1	1024	1024	3148.18	36.8031	4.81 GB (6.07%)
1	2048	2048	2927.33	35.2676	5.73 GB (7.23%)

Fused module

Batch Size	Prefill Length	Decode Length	Prefill tokens/s	Decode tokens/s	Memory (VRAM)
1	32	32	81.4899	80.2569	4.00 GB (5.05%)
1	64	64	1756.1	106.26	4.00 GB (5.05%)
1	128	128	2479.32	105.631	4.00 GB (5.06%)
1	256	256	1813.6	85.7485	4.01 GB (5.06%)
1	512	512	2848.9	97.701	4.11 GB (5.19%)
1	1024	1024	3044.35	87.7323	4.41 GB (5.57%)
1	2048	2048	2715.11	89.4709	5.57 GB (7.04%)

The speed and throughput of fused and unfused modules were also tested with the optimum-benchmark library.

forward peak memory/batch size

generate throughput/batch size

ExLlama-v2 support

Recent versions of autoawq supports ExLlama-v2 kernels for faster prefill and decoding. To get started, first install the latest version of autoawq by running:

pip install git+https://github.com/casper-hansen/AutoAWQ.git

Get started by passing an AwqConfig() with version="exllama".

import torch
from transformers import AutoModelForCausalLM, AutoTokenizer, AwqConfig

quantization_config = AwqConfig(version="exllama")

model = AutoModelForCausalLM.from_pretrained(
    "TheBloke/Mistral-7B-Instruct-v0.1-AWQ",
    quantization_config=quantization_config,
    device_map="auto",
)

input_ids = torch.randint(0, 100, (1, 128), dtype=torch.long, device="cuda")
output = model(input_ids)
print(output.logits)

tokenizer = AutoTokenizer.from_pretrained("TheBloke/Mistral-7B-Instruct-v0.1-AWQ")
input_ids = tokenizer.encode("How to make a cake", return_tensors="pt").to(model.device)
output = model.generate(input_ids, do_sample=True, max_length=50, pad_token_id=50256)
print(tokenizer.decode(output[0], skip_special_tokens=True))

Note this feature is supported on AMD GPUs.

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