DeAR-3B-Reranker-RankNet-LoRA-v1 is a LoRA adapter for the most efficient reranker in the DeAR family. This ultra-lightweight adapter (~40MB) achieves fast inference speeds while maintaining competitive accuracy, making it ideal for resource-constrained production environments.

Model Details

Model Type: LoRA Adapter for Pointwise Reranking
Base Model: meta-llama/Llama-3.2-3B
Adapter Size: ~40MB
Training Method: LoRA with RankNet Loss + Knowledge Distillation
LoRA Rank: 16
LoRA Alpha: 32
Trainable Parameters: 25M (0.8% of total)

Key Features

✅ Ultra Lightweight: Only 40MB storage
✅ Fastest Inference: 1.5s for 100 documents
✅ Memory Efficient: 10GB GPU for inference
✅ Easy Deployment: Quick adapter loading
✅ Cost Effective: Minimal compute requirements

Usage

Load and Use

python

import torch
from transformers import AutoTokenizer, AutoModelForSequenceClassification
from peft import PeftModel, PeftConfig

# Load LoRA adapter
adapter_path = "abdoelsayed/dear-3b-reranker-ranknet-lora-v1"
config = PeftConfig.from_pretrained(adapter_path)

# Load tokenizer
tokenizer = AutoTokenizer.from_pretrained(config.base_model_name_or_path)
if tokenizer.pad_token is None:
    tokenizer.pad_token = tokenizer.eos_token

# Load base model
base_model = AutoModelForSequenceClassification.from_pretrained(
    config.base_model_name_or_path,
    num_labels=1,
    torch_dtype=torch.bfloat16
)

# Load and merge LoRA
model = PeftModel.from_pretrained(base_model, adapter_path)
model = model.merge_and_unload()
model.eval().cuda()

# Use model
query = "What is machine learning?"
document = "Machine learning is a subset of artificial intelligence..."

inputs = tokenizer(
    f"query: {query}",
    f"document: {document}",
    return_tensors="pt",
    truncation=True,
    max_length=228,
    padding="max_length"
)
inputs = {k: v.cuda() for k, v in inputs.items()}

with torch.no_grad():
    score = model(**inputs).logits.squeeze().item()
print(f"Relevance score: {score}")

Helper Function

python

from typing import List, Tuple

def load_3b_lora_ranker(adapter_path: str):
    """Load 3B LoRA adapter efficiently."""
    config = PeftConfig.from_pretrained(adapter_path)
    
    tokenizer = AutoTokenizer.from_pretrained(config.base_model_name_or_path)
    if tokenizer.pad_token is None:
        tokenizer.pad_token = tokenizer.eos_token
    
    base = AutoModelForSequenceClassification.from_pretrained(
        config.base_model_name_or_path,
        num_labels=1,
        torch_dtype=torch.bfloat16
    )
    
    model = PeftModel.from_pretrained(base, adapter_path)
    model = model.merge_and_unload()
    model.eval().cuda()
    
    return tokenizer, model

# Load once
tokenizer, model = load_3b_lora_ranker("abdoelsayed/dear-3b-reranker-ranknet-lora-v1")

# Rerank function
@torch.inference_mode()
def rerank(tokenizer, model, query: str, docs: List[Tuple[str, str]], batch_size=128):
    scores = []
    device = next(model.parameters()).device
    
    for i in range(0, len(docs), batch_size):
        batch = docs[i:i + batch_size]
        queries = [f"query: {query}"] * len(batch)
        documents = [f"document: {t} {p}" for t, p in batch]
        
        inputs = tokenizer(queries, documents, return_tensors="pt",
                         truncation=True, max_length=228, padding=True)
        inputs = {k: v.to(device) for k, v in inputs.items()}
        
        logits = model(**inputs).logits.squeeze(-1)
        scores.extend(logits.cpu().tolist())
    
    return sorted(enumerate(scores), key=lambda x: x[1], reverse=True)

Training Details

LoRA Configuration

python

{
    "r": 16,
    "lora_alpha": 32,
    "target_modules": [
        "q_proj", "v_proj", "k_proj", "o_proj",
        "gate_proj", "up_proj", "down_proj"
    ],
    "lora_dropout": 0.05,
    "bias": "none",
    "task_type": "SEQ_CLS"
}

Training Hyperparameters

Learning Rate: 1e-4
Batch Size: 8 (larger due to lower memory)
Gradient Accumulation: 2
Epochs: 2
Hardware: 4x A100 (40GB)
Training Time: ~6 hours (3x faster than full)
Memory: ~18GB per GPU

Efficiency Comparison

Storage Efficiency

LoRA Adapter: 40MB
Full 3B Model: 6GB
Full 8B Model: 16GB
Ratio: 0.67% of 3B, 0.25% of 8B

Inference Speed

3B LoRA: 1.5s (100 docs)
8B Full: 2.2s (100 docs)
Speedup: 1.47x faster than 8B

Memory Usage

3B LoRA: 10GB GPU
3B Full: 12GB GPU
8B Full: 18GB GPU

When to Use

Best for:

✅ Extreme resource constraints
✅ Multiple domain-specific versions
✅ Fast iteration cycles
✅ Edge deployment
✅ Maximum throughput

Use full 3B for:

❌ Slightly better accuracy needed
❌ No storage constraints

Use 8B for:

❌ +3 NDCG@10 accuracy gain needed

Deployment Example

python

# Minimal memory deployment
import torch
from transformers import AutoModelForSequenceClassification
from peft import PeftModel

adapter_path = "abdoelsayed/dear-3b-reranker-ranknet-lora-v1"

# Load with memory optimization
model = AutoModelForSequenceClassification.from_pretrained(
    "meta-llama/Llama-3.2-3B",
    num_labels=1,
    torch_dtype=torch.bfloat16,
    device_map="auto",
    low_cpu_mem_usage=True
)

# Load adapter
model = PeftModel.from_pretrained(model, adapter_path)
model = model.merge_and_unload()
model.eval()

# Optional: Compile for speedup
if hasattr(torch, 'compile'):
    model = torch.compile(model, mode="max-autotune")

Performance vs Size

Model Size vs NDCG@10 (TREC DL19):
├─ Teacher-13B: 73.8 (26GB)
├─ DeAR-8B-Full: 74.5 (16GB)
├─ DeAR-8B-LoRA: 74.2 (100MB + base)
├─ DeAR-3B-Full: 71.2 (6GB)
└─ DeAR-3B-LoRA: 70.9 (40MB + base) ← This model

Best Efficiency: 95% accuracy at 0.25% size of 8B!

Related Models

Full Version:

DeAR-3B-RankNet

Same Size (3B):

DeAR-3B-CE-LoRA

Larger (8B):

DeAR-8B-RankNet-LoRA

Resources:

Citation

bibtex

@article{abdallah2025dear,
  title={DeAR: Dual-Stage Document Reranking with Reasoning Agents via LLM Distillation},
  author={Abdallah, Abdelrahman and Mozafari, Jamshid and Piryani, Bhawna and Jatowt, Adam},
  journal={arXiv preprint arXiv:2508.16998},
  year={2025}
}

License

MIT License

More Information

GitHub: DataScienceUIBK/DeAR-Reranking
Paper: arXiv:2508.16998
Collection: DeAR Models