Quantization Aware Training with NNCF, using PyTorch framework#

This Jupyter notebook can be launched after a local installation only.

Github

This notebook is based on ImageNet training in PyTorch.

The goal of this notebook is to demonstrate how to use the Neural Network Compression Framework NNCF 8-bit quantization to optimize a PyTorch model for inference with OpenVINO Toolkit. The optimization process contains the following steps:

  • Transforming the original FP32 model to INT8

  • Using fine-tuning to improve the accuracy.

  • Exporting optimized and original models to OpenVINO IR

  • Measuring and comparing the performance of models.

For more advanced usage, refer to these examples.

This tutorial uses the ResNet-18 model with the Tiny ImageNet-200 dataset. ResNet-18 is the version of ResNet models that contains the fewest layers (18). Tiny ImageNet-200 is a subset of the larger ImageNet dataset with smaller images. The dataset will be downloaded in the notebook. Using the smaller model and dataset will speed up training and download time. To see other ResNet models, visit PyTorch hub.

NOTE: This notebook requires a C++ compiler for compiling PyTorch custom operations for quantization. For Windows we recommend to install Visual Studio with C++ support, you can find instruction here. For MacOS xcode-select --install command installs many developer tools, including C++. For Linux you can install gcc with your distribution’s package manager.

Table of contents:#

%pip install -q --extra-index-url https://download.pytorch.org/whl/cpu  "openvino>=2024.0.0" "torch" "torchvision" "tqdm"
%pip install -q "nncf>=2.9.0"
DEPRECATION: pytorch-lightning 1.6.5 has a non-standard dependency specifier torch>=1.8.*. pip 24.1 will enforce this behaviour change. A possible replacement is to upgrade to a newer version of pytorch-lightning or contact the author to suggest that they release a version with a conforming dependency specifiers. Discussion can be found at pypa/pip#12063
Note: you may need to restart the kernel to use updated packages.
DEPRECATION: pytorch-lightning 1.6.5 has a non-standard dependency specifier torch>=1.8.*. pip 24.1 will enforce this behaviour change. A possible replacement is to upgrade to a newer version of pytorch-lightning or contact the author to suggest that they release a version with a conforming dependency specifiers. Discussion can be found at pypa/pip#12063
Note: you may need to restart the kernel to use updated packages.

Imports and Settings#

On Windows, add the required C++ directories to the system PATH.

Import NNCF and all auxiliary packages from your Python code. Set a name for the model, and the image width and height that will be used for the network. Also define paths where PyTorch and OpenVINO IR versions of the models will be stored.

NOTE: All NNCF logging messages below ERROR level (INFO and WARNING) are disabled to simplify the tutorial. For production use, it is recommended to enable logging by removing set_log_level(logging.ERROR).

import time
import warnings  # To disable warnings on export model
import zipfile
from pathlib import Path

import torch

import torch.nn as nn
import torch.nn.parallel
import torch.optim
import torch.utils.data
import torch.utils.data.distributed
import torchvision.datasets as datasets
import torchvision.models as models
import torchvision.transforms as transforms

import openvino as ov
from torch.jit import TracerWarning

# Fetch `notebook_utils` module
import requests

r = requests.get(
    url="https://raw.githubusercontent.com/openvinotoolkit/openvino_notebooks/latest/utils/notebook_utils.py",
)

open("notebook_utils.py", "w").write(r.text)
from notebook_utils import download_file

torch.manual_seed(0)
device = torch.device("cuda" if torch.cuda.is_available() else "cpu")
print(f"Using {device} device")

MODEL_DIR = Path("model")
OUTPUT_DIR = Path("output")
DATA_DIR = Path("data")
BASE_MODEL_NAME = "resnet18"
image_size = 64

OUTPUT_DIR.mkdir(exist_ok=True)
MODEL_DIR.mkdir(exist_ok=True)
DATA_DIR.mkdir(exist_ok=True)

# Paths where PyTorch and OpenVINO IR models will be stored.
fp32_pth_path = Path(MODEL_DIR / (BASE_MODEL_NAME + "_fp32")).with_suffix(".pth")
fp32_ir_path = fp32_pth_path.with_suffix(".xml")
int8_ir_path = Path(MODEL_DIR / (BASE_MODEL_NAME + "_int8")).with_suffix(".xml")

# It is possible to train FP32 model from scratch, but it might be slow. Therefore, the pre-trained weights are downloaded by default.
pretrained_on_tiny_imagenet = True
fp32_pth_url = "https://storage.openvinotoolkit.org/repositories/nncf/openvino_notebook_ckpts/302_resnet18_fp32_v1.pth"
download_file(fp32_pth_url, directory=MODEL_DIR, filename=fp32_pth_path.name)
Using cpu device
model/resnet18_fp32.pth:   0%|          | 0.00/43.1M [00:00<?, ?B/s]
PosixPath('/opt/home/k8sworker/ci-ai/cibuilds/ov-notebook/OVNotebookOps-697/.workspace/scm/ov-notebook/notebooks/pytorch-quantization-aware-training/model/resnet18_fp32.pth')

Download Tiny ImageNet dataset

  • 100k images of shape 3x64x64

  • 200 different classes: snake, spider, cat, truck, grasshopper, gull, etc.

def download_tiny_imagenet_200(
    data_dir: Path,
    url="http://cs231n.stanford.edu/tiny-imagenet-200.zip",
    tarname="tiny-imagenet-200.zip",
):
    archive_path = data_dir / tarname
    download_file(url, directory=data_dir, filename=tarname)
    zip_ref = zipfile.ZipFile(archive_path, "r")
    zip_ref.extractall(path=data_dir)
    zip_ref.close()


def prepare_tiny_imagenet_200(dataset_dir: Path):
    # Format validation set the same way as train set is formatted.
    val_data_dir = dataset_dir / "val"
    val_annotations_file = val_data_dir / "val_annotations.txt"
    with open(val_annotations_file, "r") as f:
        val_annotation_data = map(lambda line: line.split("\t")[:2], f.readlines())
    val_images_dir = val_data_dir / "images"
    for image_filename, image_label in val_annotation_data:
        from_image_filepath = val_images_dir / image_filename
        to_image_dir = val_data_dir / image_label
        if not to_image_dir.exists():
            to_image_dir.mkdir()
        to_image_filepath = to_image_dir / image_filename
        from_image_filepath.rename(to_image_filepath)
    val_annotations_file.unlink()
    val_images_dir.rmdir()


DATASET_DIR = DATA_DIR / "tiny-imagenet-200"
if not DATASET_DIR.exists():
    download_tiny_imagenet_200(DATA_DIR)
    prepare_tiny_imagenet_200(DATASET_DIR)
    print(f"Successfully downloaded and prepared dataset at: {DATASET_DIR}")
data/tiny-imagenet-200.zip:   0%|          | 0.00/237M [00:00<?, ?B/s]
Successfully downloaded and prepared dataset at: data/tiny-imagenet-200

Pre-train Floating-Point Model#

Using NNCF for model compression assumes that a pre-trained model and a training pipeline are already in use.

This tutorial demonstrates one possible training pipeline: a ResNet-18 model pre-trained on 1000 classes from ImageNet is fine-tuned with 200 classes from Tiny-ImageNet.

Subsequently, the training and validation functions will be reused as is for quantization-aware training.

Train Function#

def train(train_loader, model, criterion, optimizer, epoch):
    batch_time = AverageMeter("Time", ":3.3f")
    losses = AverageMeter("Loss", ":2.3f")
    top1 = AverageMeter("Acc@1", ":2.2f")
    top5 = AverageMeter("Acc@5", ":2.2f")
    progress = ProgressMeter(
        len(train_loader),
        [batch_time, losses, top1, top5],
        prefix="Epoch:[{}]".format(epoch),
    )

    # Switch to train mode.
    model.train()

    end = time.time()
    for i, (images, target) in enumerate(train_loader):
        images = images.to(device)
        target = target.to(device)

        # Compute output.
        output = model(images)
        loss = criterion(output, target)

        # Measure accuracy and record loss.
        acc1, acc5 = accuracy(output, target, topk=(1, 5))
        losses.update(loss.item(), images.size(0))
        top1.update(acc1[0], images.size(0))
        top5.update(acc5[0], images.size(0))

        # Compute gradient and do opt step.
        optimizer.zero_grad()
        loss.backward()
        optimizer.step()

        # Measure elapsed time.
        batch_time.update(time.time() - end)
        end = time.time()

        print_frequency = 50
        if i % print_frequency == 0:
            progress.display(i)

Validate Function#

def validate(val_loader, model, criterion):
    batch_time = AverageMeter("Time", ":3.3f")
    losses = AverageMeter("Loss", ":2.3f")
    top1 = AverageMeter("Acc@1", ":2.2f")
    top5 = AverageMeter("Acc@5", ":2.2f")
    progress = ProgressMeter(len(val_loader), [batch_time, losses, top1, top5], prefix="Test: ")

    # Switch to evaluate mode.
    model.eval()

    with torch.no_grad():
        end = time.time()
        for i, (images, target) in enumerate(val_loader):
            images = images.to(device)
            target = target.to(device)

            # Compute output.
            output = model(images)
            loss = criterion(output, target)

            # Measure accuracy and record loss.
            acc1, acc5 = accuracy(output, target, topk=(1, 5))
            losses.update(loss.item(), images.size(0))
            top1.update(acc1[0], images.size(0))
            top5.update(acc5[0], images.size(0))

            # Measure elapsed time.
            batch_time.update(time.time() - end)
            end = time.time()

            print_frequency = 10
            if i % print_frequency == 0:
                progress.display(i)

        print(" * Acc@1 {top1.avg:.3f} Acc@5 {top5.avg:.3f}".format(top1=top1, top5=top5))
    return top1.avg

Helpers#

class AverageMeter(object):
    """Computes and stores the average and current value"""

    def __init__(self, name, fmt=":f"):
        self.name = name
        self.fmt = fmt
        self.reset()

    def reset(self):
        self.val = 0
        self.avg = 0
        self.sum = 0
        self.count = 0

    def update(self, val, n=1):
        self.val = val
        self.sum += val * n
        self.count += n
        self.avg = self.sum / self.count

    def __str__(self):
        fmtstr = "{name} {val" + self.fmt + "} ({avg" + self.fmt + "})"
        return fmtstr.format(**self.__dict__)


class ProgressMeter(object):
    def __init__(self, num_batches, meters, prefix=""):
        self.batch_fmtstr = self._get_batch_fmtstr(num_batches)
        self.meters = meters
        self.prefix = prefix

    def display(self, batch):
        entries = [self.prefix + self.batch_fmtstr.format(batch)]
        entries += [str(meter) for meter in self.meters]
        print("\t".join(entries))

    def _get_batch_fmtstr(self, num_batches):
        num_digits = len(str(num_batches // 1))
        fmt = "{:" + str(num_digits) + "d}"
        return "[" + fmt + "/" + fmt.format(num_batches) + "]"


def accuracy(output, target, topk=(1,)):
    """Computes the accuracy over the k top predictions for the specified values of k"""
    with torch.no_grad():
        maxk = max(topk)
        batch_size = target.size(0)

        _, pred = output.topk(maxk, 1, True, True)
        pred = pred.t()
        correct = pred.eq(target.view(1, -1).expand_as(pred))

        res = []
        for k in topk:
            correct_k = correct[:k].reshape(-1).float().sum(0, keepdim=True)
            res.append(correct_k.mul_(100.0 / batch_size))
        return res

Get a Pre-trained FP32 Model#

А pre-trained floating-point model is a prerequisite for quantization. It can be obtained by tuning from scratch with the code below. However, this usually takes a lot of time. Therefore, this code has already been run and received good enough weights after 4 epochs (for the sake of simplicity, tuning was not done until the best accuracy). By default, this notebook just loads these weights without launching training. To train the model yourself on a model pre-trained on ImageNet, set pretrained_on_tiny_imagenet = False in the Imports and Settings section at the top of this notebook.

num_classes = 200  # 200 is for Tiny ImageNet, default is 1000 for ImageNet
init_lr = 1e-4
batch_size = 128
epochs = 4

model = models.resnet18(pretrained=not pretrained_on_tiny_imagenet)
# Update the last FC layer for Tiny ImageNet number of classes.
model.fc = nn.Linear(in_features=512, out_features=num_classes, bias=True)
model.to(device)

# Data loading code.
train_dir = DATASET_DIR / "train"
val_dir = DATASET_DIR / "val"
normalize = transforms.Normalize(mean=[0.485, 0.456, 0.406], std=[0.229, 0.224, 0.225])

train_dataset = datasets.ImageFolder(
    train_dir,
    transforms.Compose(
        [
            transforms.Resize(image_size),
            transforms.RandomHorizontalFlip(),
            transforms.ToTensor(),
            normalize,
        ]
    ),
)
val_dataset = datasets.ImageFolder(
    val_dir,
    transforms.Compose(
        [
            transforms.Resize(image_size),
            transforms.ToTensor(),
            normalize,
        ]
    ),
)

train_loader = torch.utils.data.DataLoader(
    train_dataset,
    batch_size=batch_size,
    shuffle=True,
    num_workers=0,
    pin_memory=True,
    sampler=None,
)

val_loader = torch.utils.data.DataLoader(val_dataset, batch_size=batch_size, shuffle=False, num_workers=0, pin_memory=True)

# Define loss function (criterion) and optimizer.
criterion = nn.CrossEntropyLoss().to(device)
optimizer = torch.optim.Adam(model.parameters(), lr=init_lr)
/opt/home/k8sworker/ci-ai/cibuilds/ov-notebook/OVNotebookOps-697/.workspace/scm/ov-notebook/.venv/lib/python3.8/site-packages/torchvision/models/_utils.py:208: UserWarning: The parameter 'pretrained' is deprecated since 0.13 and may be removed in the future, please use 'weights' instead.
  warnings.warn(
/opt/home/k8sworker/ci-ai/cibuilds/ov-notebook/OVNotebookOps-697/.workspace/scm/ov-notebook/.venv/lib/python3.8/site-packages/torchvision/models/_utils.py:223: UserWarning: Arguments other than a weight enum or None for 'weights' are deprecated since 0.13 and may be removed in the future. The current behavior is equivalent to passing weights=None.
  warnings.warn(msg)
if pretrained_on_tiny_imagenet:
    #
    # ** WARNING: The `torch.load` functionality uses Python's pickling module that
    # may be used to perform arbitrary code execution during unpickling. Only load data that you
    # trust.
    #
    checkpoint = torch.load(str(fp32_pth_path), map_location="cpu")
    model.load_state_dict(checkpoint["state_dict"], strict=True)
    acc1_fp32 = checkpoint["acc1"]
else:
    best_acc1 = 0
    # Training loop.
    for epoch in range(0, epochs):
        # Run a single training epoch.
        train(train_loader, model, criterion, optimizer, epoch)

        # Evaluate on validation set.
        acc1 = validate(val_loader, model, criterion)

        is_best = acc1 > best_acc1
        best_acc1 = max(acc1, best_acc1)

        if is_best:
            checkpoint = {"state_dict": model.state_dict(), "acc1": acc1}
            torch.save(checkpoint, fp32_pth_path)
    acc1_fp32 = best_acc1

print(f"Accuracy of FP32 model: {acc1_fp32:.3f}")
Accuracy of FP32 model: 55.520

Export the FP32 model to OpenVINO™ Intermediate Representation, to benchmark it in comparison with the INT8 model.

dummy_input = torch.randn(1, 3, image_size, image_size).to(device)

ov_model = ov.convert_model(model, example_input=dummy_input, input=[1, 3, image_size, image_size])
ov.save_model(ov_model, fp32_ir_path, compress_to_fp16=False)
print(f"FP32 model was exported to {fp32_ir_path}.")
FP32 model was exported to model/resnet18_fp32.xml.

Create and Initialize Quantization#

NNCF enables compression-aware training by integrating into regular training pipelines. The framework is designed so that modifications to your original training code are minor. Quantization requires only 2 modifications.

  1. Create a quantization data loader with batch size equal to one and wrap it by the nncf.Dataset, specifying a transformation function which prepares input data to fit into model during quantization. In our case, to pick input tensor from pair (input tensor and label).

import nncf


def transform_fn(data_item):
    return data_item[0]


# Creating separate dataloader with batch size = 1
# as dataloaders with batches > 1 is not supported yet.
quantization_loader = torch.utils.data.DataLoader(val_dataset, batch_size=1, shuffle=False, num_workers=0, pin_memory=True)

quantization_dataset = nncf.Dataset(quantization_loader, transform_fn)
INFO:nncf:NNCF initialized successfully. Supported frameworks detected: torch, tensorflow, onnx, openvino
  1. Run nncf.quantize for Getting an Optimized Model.

nncf.quantize function accepts model and prepared quantization dataset for performing basic quantization. Optionally, additional parameters like subset_size, preset, ignored_scope can be provided to improve quantization result if applicable. More details about supported parameters can be found on this page

quantized_model = nncf.quantize(model, quantization_dataset)
2024-06-06 01:21:39.441995: I tensorflow/core/util/port.cc:110] oneDNN custom operations are on. You may see slightly different numerical results due to floating-point round-off errors from different computation orders. To turn them off, set the environment variable TF_ENABLE_ONEDNN_OPTS=0.
2024-06-06 01:21:39.478111: I tensorflow/core/platform/cpu_feature_guard.cc:182] This TensorFlow binary is optimized to use available CPU instructions in performance-critical operations.
To enable the following instructions: AVX2 AVX512F AVX512_VNNI FMA, in other operations, rebuild TensorFlow with the appropriate compiler flags.
2024-06-06 01:21:40.003115: W tensorflow/compiler/tf2tensorrt/utils/py_utils.cc:38] TF-TRT Warning: Could not find TensorRT
Output()
INFO:nncf:Compiling and loading torch extension: quantized_functions_cpu...
INFO:nncf:Finished loading torch extension: quantized_functions_cpu
Output()

Evaluate the new model on the validation set after initialization of quantization. The accuracy should be close to the accuracy of the floating-point FP32 model for a simple case like the one being demonstrated here.

acc1 = validate(val_loader, quantized_model, criterion)
print(f"Accuracy of initialized INT8 model: {acc1:.3f}")
Test: [ 0/79]       Time 0.217 (0.217)      Loss 1.005 (1.005)      Acc@1 78.91 (78.91)     Acc@5 88.28 (88.28)
Test: [10/79]       Time 0.176 (0.179)      Loss 1.992 (1.625)      Acc@1 44.53 (60.37)     Acc@5 79.69 (83.66)
Test: [20/79]       Time 0.169 (0.176)      Loss 1.814 (1.705)      Acc@1 60.94 (58.04)     Acc@5 80.47 (82.66)
Test: [30/79]       Time 0.169 (0.174)      Loss 2.287 (1.795)      Acc@1 50.78 (56.48)     Acc@5 68.75 (80.97)
Test: [40/79]       Time 0.171 (0.174)      Loss 1.615 (1.832)      Acc@1 60.94 (55.43)     Acc@5 82.81 (80.43)
Test: [50/79]       Time 0.170 (0.173)      Loss 1.952 (1.833)      Acc@1 57.03 (55.51)     Acc@5 75.00 (80.16)
Test: [60/79]       Time 0.198 (0.174)      Loss 1.794 (1.856)      Acc@1 57.03 (55.16)     Acc@5 84.38 (79.84)
Test: [70/79]       Time 0.173 (0.174)      Loss 2.371 (1.889)      Acc@1 46.88 (54.68)     Acc@5 74.22 (79.14)
 * Acc@1 55.040 Acc@5 79.730
Accuracy of initialized INT8 model: 55.040

Fine-tune the Compressed Model#

At this step, a regular fine-tuning process is applied to further improve quantized model accuracy. Normally, several epochs of tuning are required with a small learning rate, the same that is usually used at the end of the training of the original model. No other changes in the training pipeline are required. Here is a simple example.

compression_lr = init_lr / 10
optimizer = torch.optim.Adam(quantized_model.parameters(), lr=compression_lr)

# Train for one epoch with NNCF.
train(train_loader, quantized_model, criterion, optimizer, epoch=0)

# Evaluate on validation set after Quantization-Aware Training (QAT case).
acc1_int8 = validate(val_loader, quantized_model, criterion)

print(f"Accuracy of tuned INT8 model: {acc1_int8:.3f}")
print(f"Accuracy drop of tuned INT8 model over pre-trained FP32 model: {acc1_fp32 - acc1_int8:.3f}")
Epoch:[0][  0/782]  Time 0.436 (0.436)      Loss 1.029 (1.029)      Acc@1 75.00 (75.00)     Acc@5 90.62 (90.62)
Epoch:[0][ 50/782]  Time 0.375 (0.377)      Loss 0.672 (0.823)      Acc@1 87.50 (79.81)     Acc@5 94.53 (93.84)
Epoch:[0][100/782]  Time 0.369 (0.376)      Loss 0.661 (0.799)      Acc@1 85.94 (80.31)     Acc@5 98.44 (94.41)
Epoch:[0][150/782]  Time 0.374 (0.375)      Loss 0.632 (0.797)      Acc@1 85.94 (80.50)     Acc@5 94.53 (94.24)
Epoch:[0][200/782]  Time 0.373 (0.375)      Loss 0.742 (0.790)      Acc@1 81.25 (80.69)     Acc@5 94.53 (94.31)
Epoch:[0][250/782]  Time 0.376 (0.375)      Loss 0.815 (0.785)      Acc@1 81.25 (80.80)     Acc@5 93.75 (94.34)
Epoch:[0][300/782]  Time 0.376 (0.374)      Loss 0.878 (0.781)      Acc@1 76.56 (80.87)     Acc@5 92.19 (94.37)
Epoch:[0][350/782]  Time 0.367 (0.375)      Loss 0.746 (0.774)      Acc@1 82.03 (81.03)     Acc@5 93.75 (94.44)
Epoch:[0][400/782]  Time 0.374 (0.374)      Loss 0.766 (0.772)      Acc@1 79.69 (81.12)     Acc@5 96.88 (94.42)
Epoch:[0][450/782]  Time 0.375 (0.374)      Loss 0.865 (0.768)      Acc@1 77.34 (81.28)     Acc@5 93.75 (94.48)
Epoch:[0][500/782]  Time 0.380 (0.374)      Loss 0.526 (0.765)      Acc@1 89.06 (81.33)     Acc@5 97.66 (94.53)
Epoch:[0][550/782]  Time 0.373 (0.374)      Loss 0.826 (0.762)      Acc@1 79.69 (81.39)     Acc@5 92.19 (94.55)
Epoch:[0][600/782]  Time 0.376 (0.374)      Loss 0.644 (0.761)      Acc@1 85.94 (81.45)     Acc@5 95.31 (94.55)
Epoch:[0][650/782]  Time 0.374 (0.374)      Loss 0.585 (0.757)      Acc@1 81.25 (81.57)     Acc@5 98.44 (94.59)
Epoch:[0][700/782]  Time 0.374 (0.374)      Loss 0.578 (0.755)      Acc@1 86.72 (81.65)     Acc@5 96.88 (94.60)
Epoch:[0][750/782]  Time 0.379 (0.374)      Loss 0.783 (0.753)      Acc@1 79.69 (81.69)     Acc@5 95.31 (94.63)
Test: [ 0/79]       Time 0.151 (0.151)      Loss 1.063 (1.063)      Acc@1 74.22 (74.22)     Acc@5 87.50 (87.50)
Test: [10/79]       Time 0.153 (0.152)      Loss 1.785 (1.514)      Acc@1 50.78 (63.21)     Acc@5 81.25 (84.38)
Test: [20/79]       Time 0.152 (0.153)      Loss 1.582 (1.588)      Acc@1 64.84 (61.09)     Acc@5 82.03 (84.04)
Test: [30/79]       Time 0.153 (0.153)      Loss 2.103 (1.691)      Acc@1 55.47 (59.30)     Acc@5 71.09 (82.41)
Test: [40/79]       Time 0.153 (0.153)      Loss 1.597 (1.745)      Acc@1 64.06 (57.89)     Acc@5 83.59 (81.48)
Test: [50/79]       Time 0.154 (0.153)      Loss 1.895 (1.751)      Acc@1 53.91 (57.74)     Acc@5 77.34 (81.20)
Test: [60/79]       Time 0.154 (0.153)      Loss 1.566 (1.783)      Acc@1 65.62 (57.18)     Acc@5 84.38 (80.75)
Test: [70/79]       Time 0.153 (0.153)      Loss 2.457 (1.811)      Acc@1 45.31 (56.65)     Acc@5 73.44 (80.27)
 * Acc@1 57.080 Acc@5 80.940
Accuracy of tuned INT8 model: 57.080
Accuracy drop of tuned INT8 model over pre-trained FP32 model: -1.560

Export INT8 Model to OpenVINO IR#

if not int8_ir_path.exists():
    warnings.filterwarnings("ignore", category=TracerWarning)
    warnings.filterwarnings("ignore", category=UserWarning)
    # Export INT8 model to OpenVINO™ IR
    ov_model = ov.convert_model(quantized_model, example_input=dummy_input, input=[1, 3, image_size, image_size])
    ov.save_model(ov_model, int8_ir_path)
    print(f"INT8 model exported to {int8_ir_path}.")
WARNING:tensorflow:Please fix your imports. Module tensorflow.python.training.tracking.base has been moved to tensorflow.python.trackable.base. The old module will be deleted in version 2.11.
INT8 model exported to model/resnet18_int8.xml.

Benchmark Model Performance by Computing Inference Time#

Finally, measure the inference performance of the FP32 and INT8 models, using Benchmark Tool - inference performance measurement tool in OpenVINO. By default, Benchmark Tool runs inference for 60 seconds in asynchronous mode on CPU. It returns inference speed as latency (milliseconds per image) and throughput (frames per second) values.

NOTE: This notebook runs benchmark_app for 15 seconds to give a quick indication of performance. For more accurate performance, it is recommended to run benchmark_app in a terminal/command prompt after closing other applications. Run benchmark_app -m model.xml -d CPU to benchmark async inference on CPU for one minute. Change CPU to GPU to benchmark on GPU. Run benchmark_app --help to see an overview of all command-line options.

import ipywidgets as widgets

# Initialize OpenVINO runtime
core = ov.Core()
device = widgets.Dropdown(
    options=core.available_devices,
    value="CPU",
    description="Device:",
    disabled=False,
)

device
Dropdown(description='Device:', options=('CPU',), value='CPU')
def parse_benchmark_output(benchmark_output):
    parsed_output = [line for line in benchmark_output if "FPS" in line]
    print(*parsed_output, sep="\n")


print("Benchmark FP32 model (IR)")
benchmark_output = ! benchmark_app -m $fp32_ir_path -d $device.value -api async -t 15
parse_benchmark_output(benchmark_output)

print("Benchmark INT8 model (IR)")
benchmark_output = ! benchmark_app -m $int8_ir_path -d $device.value -api async -t 15
parse_benchmark_output(benchmark_output)
Benchmark FP32 model (IR)
[ INFO ] Throughput:   2941.82 FPS
Benchmark INT8 model (IR)
[ INFO ] Throughput:   11834.02 FPS

Show Device Information for reference.

core.get_property(device.value, "FULL_DEVICE_NAME")
'Intel(R) Core(TM) i9-10920X CPU @ 3.50GHz'