Real Time Global Tests of the ALICE High Level Trigger Data Transport Framework

TL;DR

This paper reports on real-time, global-scale testing of the ALICE High Level Trigger data transport framework, demonstrating its scalability and low latency across extensive distances in a high-throughput environment.

Contribution

It presents the first large-scale, real-time, global test of the ALICE HLT data transport framework across multiple sites over 10,000 km.

Findings

Successful operation over five sites across 10,000 km

Low latency and high throughput achieved in real-time

Framework scalable for global high-energy physics experiments

Abstract

The High Level Trigger (HLT) system of the ALICE experiment is an online event filter and trigger system designed for input bandwidths of up to 25 GB/s at event rates of up to 1 kHz. The system is designed as a scalable PC cluster, implementing several hundred nodes. The transport of data in the system is handled by an object-oriented data flow framework operating on the basis of the publisher-subscriber principle, being designed fully pipelined with lowest processing overhead and communication latency in the cluster. In this paper, we report the latest measurements where this framework has been operated on five different sites over a global north-south link extending more than 10,000 km, processing a ``real-time'' data flow.