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SSQL-ECCV2022

Official code for Synergistic Self-supervised and Quantization Learning (Accepted to ECCV 2022 oral presentation).

Paper is now available at [arxiv].

Introduction

In this paper, we propose a method called synergistic self-supervised and quantization learning (SSQL) to pretrain quantization-friendly self-supervised models facilitating downstream deployment. SSQL contrasts the features of the quantized and full precision models in a self-supervised fashion, where the bit-width for the quantized model is randomly selected in each step. SSQL not only significantly improves the accuracy when quantized to lower bit-widths, but also boosts the accuracy of full precision models in most cases. By only training once, SSQL can then benefit various downstream tasks at different bit-widths simultaneously. Moreover, the bit-width flexibility is achieved without additional storage overhead, requiring only one copy of weights during training and inference. We theoretically analyze the optimization process of SSQL, and conduct exhaustive experiments on various benchmarks to further demonstrate the effectiveness of our method.

Getting Started

Prerequisites

• Python 3
• PyTorch (= 1.10.0)
• Torchvision (= 0.11.1)
• Numpy
• CUDA 10.1

All dataset definitions are in the datasets folder. By default, the form of PyTorch's train/val folder is used. You can specify the path of the dataset yourself in the corresponding dataset file.

We used 4 2080Ti GPUs for CIFAR experiments (except for ResNet-50) and 8 2080Ti GPUs for ImageNet experiments.

CIFAR Experiments

• Pre-training stage using SSQL (c.f. scripts/cifar/run_Qsimsiam.sh), run:

python -m torch.distributed.launch --nproc_per_node=4 --use_env main.py \
    ssl --config ./configs/cifar/resnet18_ssql_simsiam_cifar.yaml \
    --output [your_checkpoint_dir] -j 8

You can set hyper-parameters manually in the corresponding .yaml file (e.g., configs/cifar/resnet18_ssql_simsiam_cifar.yaml here).

TRAIN:
    EPOCHS: 400 # Total training epochs
    DATASET: cifar10 # Specify datasets
    BATCH_SIZE: 128 # batch-size for each gpu
    OPTIMIZER: 
        NAME: sgd
        MOMENTUM: 0.9
        WEIGHT_DECAY: 0.0005
    LR_SCHEDULER:
        WARMUP_EPOCHS: 0
        BASE_LR: 0.05  
        MIN_LR: 0.
        TYPE: cosine # lr scheduler
    LOSS: 
        CRITERION:
            NAME: CosineSimilarity # loss function
QUANT:
    W:
        BIT_RANGE: [2, 9] # the bit range for weights in SSQL
    A:
        BIT_RANGE: [4, 9] # the bit range for activation in SSQL
SSL:
    TYPE: SSQL_SimSiam # SSL algorithm type
    SETTING:
        DIM: 2048 # dimension for the output feature
        HIDDEN_DIM: 2048 # dimension for the hidden MLP

• You can also use other baseline methods for pre-training. For example, you can run scripts/cifar/run_simsiam.sh for SimSiam, scripts/cifar/run_moco.sh for MoCo.

• Linear evaluation stage using pre-trained models (c.f. scripts/cifar/run_linear_eval.sh), run:

python -m torch.distributed.launch --nproc_per_node=4 --use_env main.py \
    linear  --config ./configs/cifar/resnet18_linear_eval_cifar.yaml \
    --output [output_dir] -j 8

To specify the pre-trained model path and evaluation bit-width, you need to mannually modify the .yaml file (configs/cifar/resnet18_linear_eval_cifar.yaml). For instance, our pretrained model is ./checkpoint.pth.tar and we want to evaluate it with weight and activation both quantized to 4 bits (i.e., 4w4f), the modification in yaml file should look like

MODEL:
    PRETRAINED: ./checkpoint.pth.tar # you need to change here
QUANT:
    TYPE: ptq
    W:
        BIT: 4 # you need to change here
        SYMMETRY: True
        QUANTIZER: uniform
        GRANULARITY : channelwise
        OBSERVER_METHOD:
            NAME: MINMAX
    A:
        BIT: 4 # you need to change here
        SYMMETRY: False
        QUANTIZER: uniform
        GRANULARITY : layerwise
        OBSERVER_METHOD:
            NAME: MINMAX

ImageNet Experiments

Pre-training and Linear Evaluation

• Pre-training stage using SSQL (c.f. scripts/imagenet/run_Qsimsiam_imagenet.sh), run:

python -m torch.distributed.launch --nproc_per_node=8 --use_env main.py \
    ssl --config ./configs/imagenet/resnet18_ssql_simsiam_imagenet.yaml \
    --output [your_checkpoint_dir] -j 8

• Linear evaluation on ImageNet (c.f. scripts/imagenet/run_linear_eval_imagenet.sh). If you want to specify the model weights and quantization bits, see the instructions on CIFAR above and modify the corresponding configs/imagenet/resnet18_linear_eval_imagenet.yaml.

Transferring Experiments

[To be updated]

Join Us

Welcome to be a member (or an intern) of our team if you are interested in Quantization, Pruning, Distillation, Self-Supervised Learning and Model Deployment. Please send your resume to sunpeiqin@megvii.com.

Citation

Please consider citing our work in your publications if it helps your research.

@article{SSQL,
   title         = {Synergistic Self-supervised and Quantization Learning},
   author        = {Yun-Hao Cao, Peiqin Sun, Yechang Huang, Jianxin Wu and Shuchang Zhou},
   year          = {2022},
   booktitle = {The European Conference on Computer Vision}}