SDXL-1 to ONNX conversion

Hi i am facing issue in Quantization on SDXL 1 when i export UNet component to .ONNX model and the i am not able to create .ONNX Model

when i export using the code given below it export the unet.ONNX model of 4mb which is too small

and also facing an issue while loading it for inference

actually i want to quantized the model and used for edge devices for image to image inference to save memory and time could you guide me completely to Quantized the SDXL-1

!pip install -q diffusers transformers accelerate onnx onnxruntime
from diffusers import UNet2DConditionModel
import torch

Load the UNet model from SDXL
unet = UNet2DConditionModel.from_pretrained(
"stabilityai/stable-diffusion-xl-base-1.0",
subfolder="unet",
torch_dtype=torch.float32 # use float32 for export
)
unet.eval()
import torch.nn as nn

class UNetWrapper(nn.Module):
def init(self, unet):
super().init()
self.unet = unet

def forward(self, sample, timestep, encoder_hidden_states, text_embeds, time_ids):
added_cond_kwargs = {
"text_embeds": text_embeds,
"time_ids": time_ids
}
return self.unet(
sample=sample,
timestep=timestep,
encoder_hidden_states=encoder_hidden_states,
added_cond_kwargs=added_cond_kwargs
).sample
sample = torch.randn(1, 4, 64, 64) # latent input
timestep = torch.tensor([10], dtype=torch.int64) # denoising step
encoder_hidden_states = torch.randn(1, 77, 2048) # text encoder output
text_embeds = torch.randn(1, 1280) # pooled text embeddings
time_ids = torch.randn(1, 6) # time conditioning vector
from pathlib import Path

Define output path
onnx_path = "/content/drive/MyDrive/Umair/SkinCare/Quantization/Dynamic Quantization unet/unet_sdxl.onnx"
Path(onnx_path).parent.mkdir(parents=True, exist_ok=True)

Export the model
torch.onnx.export(
UNetWrapper(unet),
(sample, timestep, encoder_hidden_states, text_embeds, time_ids),
onnx_path,
input_names=["sample", "timestep", "encoder_hidden_states", "text_embeds", "time_ids"],
output_names=["out_sample"],
dynamic_axes={
"sample": {0: "batch"},
"encoder_hidden_states": {0: "batch"},
"text_embeds": {0: "batch"},
"time_ids": {0: "batch"},
"out_sample": {0: "batch"},
},
opset=17
)

print("✅ UNet exported successfully to:", onnx_path)
from onnxruntime.quantization import quantize_dynamic, QuantType

quantized_path = onnx_path.replace(".onnx", "_int8.onnx")

quantize_dynamic(
model_input=onnx_path,
model_output=quantized_path,
weight_type=QuantType.QInt8
)

print("✅ Quantized model saved to:", quantized_path)

code to check the size of .onnx and _int8.onnx

print(f".onnx file size: {os.path.getsize(onnx_model_path) / (10241024):.2f} MB")
print(f"_int8.onnx file size: {os.path.getsize(quant_model_path) / (10241024):.2f} MB")

.onnx file size: 3.98 MB
_int8.onnx file size: 2458.93 MB

and also facing an issue while loading it for infrence

Start by reproducing the provided SDXL UNet export and ONNX Runtime quantization code, then inspect why the exported model is 3.98 MB while the quantized model is much larger and why inference loading fails. Done would require a valid quantized SDXL UNet model that loads successfully for inference, but the issue does not name a repository file or test to update.