Chocolate Cloud SkyFlok Latency Prediction: Gradient Boosting Models (ONNX)

Model Info

This repository contains a collection of machine learning models developed in collaboration between University College Dublin (UCD) and Chocolate Cloud (CC).

These models are deployed within the SkyFlok Gateway component (hosted in London). They perform Latency Prediction to estimate the time required to retrieve a file from specific cloud storage backends.

By predicting download times based on temporal patterns and file size, these models enable the Gateway to intelligently route download requests to the fastest available storage region. This minimizes retrieval latency and optimizes network efficiency for the end user.

The models are exported in ONNX format (Opset 18) to ensure high-performance, low-latency inference within the real-time routing logic.

Purpose

These models perform Regression to predict a continuous value:

• Input: File size and detailed timestamps (Hour, Day, Time of Day).
• Output: Estimated Transfer Time (Latency) in milliseconds.

Repository Structure & Backend Mapping

Since latency characteristics vary between cloud providers, a separate model is trained for each storage backend. Use the table below to identify which model corresponds to which cloud provider/region.

Directory Layout

/models
    ├── model_backend_id_4.onnx    # Model for Backend ID 4
    ├── model_backend_id_20.onnx   # Model for Backend ID 20
    ├── model_backend_id_39.onnx   # ...
    ├── model_backend_id_79.onnx
    ├── model_backend_id_137.onnx
    └── model_backend_id_144.onnx
    └── model_config.json          # Hyperparameters & metadata

Training Data

The models were trained on historical transfer logs collected from the SkyFlok platform.

The dataset captures real-world network performance metrics across different times of day and days of the week.

Features Used:

• Workload: File size (bytes).
• Temporal: Time of day (categorical: morning, afternoon, etc.), Hour, Minute, Second, Day of Week.

Model Architecture

These models utilize a Scikit-Learn Pipeline architecture, fully converted to ONNX:

1. Preprocessing: A ColumnTransformer that handles mixed data types (One-Hot Encoding for strings, pass-through for numbers). 2. Regressor: Gradient Boosting Regressor (2000 trees, Max Depth 12).

This architecture allows the model to capture complex, non-linear relationships between network congestion (time of day) and transfer speeds.

Model Specification (Common Interface)

All models in this collection share the same input/output interface specifications.

Inputs

The models accept a dictionary of standard Python lists.

Note: The double brackets [[ ]] are required to represent a batch size of 1.

Outputs

• Name: predicted_latency
• Data Type: float32
• Shape: [batch_size, 1]
• Unit: Milliseconds (ms)

Limitations

• Backend Specificity: model_backend_id_4.onnx is trained specifically on the performance history of Backend #4. It should not be used to predict latency for other backends.
• Historical Bias: Predictions are based on historical trends; sudden network outages or unprecedented congestion events may result in prediction errors.

Usage Demo

To run any model from this collection, follow the steps below.

1. Setup Environment

python3.13 -m venv venv
source venv/bin/activate
pip install onnxruntime

2. Run Inference

python inference_demo.py

Code Example

If you prefer to integrate it into your own application, here is the minimal code required:

import onnxruntime as ort
from datetime import datetime

# --- Configuration ---
backend_id = 4
file_size = 100000.0  # 100 KB

# --- Helper ---
def get_time_of_day(hour):
    if 5 <= hour < 12: return 'morning'
    elif 12 <= hour < 17: return 'afternoon'
    elif 17 <= hour < 21: return 'evening'
    return 'night'

# --- 1. Prepare Input ---
# Note: Double brackets [[ ]] create the required batch dimension (Batch=1)
t = datetime.now()
inputs = {
    'time_of_day': [[get_time_of_day(t.hour)]],
    'hour':        [[t.hour]],
    'minute':      [[t.minute]],
    'second':      [[t.second]],
    'day_of_week': [[t.strftime('%A')]],
    'size':        [[file_size]]
}

# --- 2. Run Inference ---
session = ort.InferenceSession(f"models/model_backend_id_{backend_id}.onnx")
result = session.run(None, inputs)

print(f"Predicted Latency: {result[0][0][0]:.2f} ms")

Citation

If you wish to cite this specific model collection, please use the citation generated by Zenodo (located in the right sidebar of this record).

Acknowledgement & Funding

This work is part of the MLSysOps project, funded by the European Union’s Horizon Europe research and innovation programme under grant agreement No. 101092912.

More information about the project is available at https://mlsysops.eu/