Understanding Top500: Key Insights and Facts

One-line Definition

Top500 is a list of the 500 fastest supercomputers in the world.

In a Nutshell

• First published in 1993.
• Published two times per year (June and November).
• Seen as a gauge of technological and scientific progress.
• El Capitan, from USA, is currently the most powerful supercomputer in the world.
• Green500 is a sibling list ranking supercomputers by energy efficiency.

El Capitan, the most powerful supercomputer in the world.

Essentials

1. FLOPS. The performance of systems listed in the rank is expressed as FLOPS (floating-point operations per second). It measures the amount of computing operations involving double precision decimals a computer is able to execute in a second. So, the higher the FLOPS, the higher the machine’s computing power.
2. HPL. To guarantee a fair comparison, the list uses the same benchmark to assess the performance of all supercomputers. The HPL (High Performance LINPACK) solves a dense system of linear equations in order to measure the performance delivered by the system.
3. Theoretical and maximum performance. For each supercomputer listed in the rank, we can check the theoretical (Rpeak) and real maximum performance achieved by the system (Rmax). For the purpose of ranking supercomputers, the list takes into account only the latter.

Brief Diving

• After assuming the leadership on the list, China is currently not submitting new results, probably due to the ongoing geopolitical tensions around technology supplies.
• Europe is seeking to increase its computing power through initiatives like EuroHPC JU (European High Performance Computing Joint Undertaking) which brought JUPITER to life, the fourth system in the rank.
• Although NVIDIA is undoubtedly the leader on accelerated computing, the first position on the list uses AMD accelerators.

Around 88% of systems in the last edition of Top500 are endowed with NVIDIA devices. Credit: Top500.

Fun Facts

• Frontier was the first supercomputer to reach the Exaflop milestone, in 2022.
• All continents had at least one supercomputer listed once in the rank.
• The meaning of supercomputers’s names is diverse! Some names are just acronyms (SSC-24), while other ones reference mythical beings (Selene) or honor historical figures (Leonardo) and national symbols (Harpia).

Pain Points

• HPL uses double-precision numeric format (64 bits), while AI workloads are currently using single (32 bits) and half precision (16 bits) formats, and even lower. So, using HPL as the performance benchmark for Top500 can disadvantage machines especially designed for AI.
• Because of the current concern on technological sovereignty, other countries can follow China’s strategy on not sharing information on Top500. As a result, the list can lose relevance on indicating technology and science advancements.

Further Reading

• The Top500 list
• The New South as a Frontline of the U.S.-China Technological Rivalry
• European High Performance Computing Joint Undertaking — EuroHPC JU
• Floating-Point Operations Per Second (FLOPS)
• LU Decomposition

Originally published at theparallelminds.substack.com