From S3 to GPU in One Copy: Rethinking Data Loading for ML Training

QCon London 2026

Session Machine Learning Infrastructure

From S3 to GPU in One Copy: Rethinking Data Loading for ML Training

Tuesday Mar 17 / 11:45AM GMT, Windsor (5th Fl.) at The QEII Centre, London

Abstract

ML training pipelines treat data as static. Teams spend weeks preprocessing datasets into WebDataset or TFRecords, and when they want to experiment with curriculum learning or data mixing, they reprocess everything from scratch. Meanwhile, GPUs sit idle waiting for data that takes the scenic route: S3 to disk, disk to CPU, CPU decompression, and finally a copy to the GPU.

What if you could scan and filter your training data on the fly, streaming it from object storage to GPU memory in a single copy, saturating the host-to-device bandwidth?

This talk introduces Vortex, an open-source columnar file format designed for this world. I'll show how the format's design enables a data path that conventional formats can't support: composable encodings that compress better and decompress on GPU, independent column chunking that minimizes bytes on the wire, and a layout tree that turns a query into precise byte-range reads from S3. No CPU in the data path.

You'll learn how Vortex differs from Parquet, how we built a single-copy S3 to GPU pipeline on top of it, and where this is heading next.

For ML infrastructure engineers tired of the preprocessing treadmill.

Topics

Machine Learning Infrastructure GPU File Formats Performance Engineering
76% senior dev or higher
1:11 speaker ratio
60+ practitioners

QCon London 2026 is a three day conference for senior software engineers, architects and team leads. An international program committee of working engineers selects every session. Patterns and practices, not products and pitches.

Share

From the same track

Tuesday 17 March

10:35 Fleming (3rd Fl.) Session Generative AI Ontology‐Driven Observability: Building the E2E Knowledge Graph at Netflix Scale Prasanna Vijayanathan, Renzo Sanchez-Silva 11:45 Windsor (5th Fl.) Session Machine Learning Infrastructure From S3 to GPU in One Copy: Rethinking Data Loading for ML Training Onur Satici Staff Engineer @SpiralDB & a Core Maintainer of Vortex (LF AI & Data), Previously Building Distributed Systems @Palantir 13:35 Whittle (3rd Fl.) Session Kafka Introducing Tansu.io -- Rethinking Kafka for Lean Operations Peter Morgan Founder @tansu.io 14:45 Mountbatten (6th Fl.) Session AI/ML Chronon - Mixed-Workload Data Processing Framework Nikhil Simha Co-Founder & CTO @zipline.ai, Author of "Chronon Feature Platform", Previously @Airbnb, @Meta, and @Walmartlabs 15:55 Whittle (3rd Fl.) Session streaming The Rise of the Streamhouse: Idea, Trade-Offs, and Evolution Giannis Polyzos, Anton Borisov 17:05 Rutherford (4th Fl.) Event Connecting the Dots: Modern Data Engineering & Architectures (Limited Space - Registration Required)