The TOP500 rank is not a count of nodes, GPUs, or aggregate FLOPS.
Many systems have the node count to be able to run such benchmarks, but are not optimized or even capable of running them. Having these systems run these large calculations in a sustained way, and performing, is what separates a bunch of nodes together in a data center from an actual cluster that is able to run a benchmark like HPL or HPCG.
To sustain 70 - 80% of peak performance across hundreds of thousands of cores, you need a real low-diameter, high-bandwidth, low-latency fabric and a balanced memory subsystem, running on a system w almost no failures or network issues. A loosely-coupled cluster with an oversubscribed fat-tree will 'run Linpack' and then post an Rmax that's a small fraction of its naive peak.
Also, have a look at the Green500, and the systems there. This is not about bragging rights vendors, this is about placing commodity hardware, tuning it, and bringing it up to health in a way that squeezes all of that last performance possible out of the clusters on those lists. That's the opposite of vendor flexing - it's a craft that you cannot see in a simple node count, as some have been comparing here.
If you ever worked on this field, and with the vendors at this scale, you would know. Its not easy, its actually very hard.
... and imagine you need to deploy this, systems at this scale, w technologies that are sometimes just emerging and sometimes even need proper field testing * every 6 months * to be able to reach the scale and stability to land on these lists.
Many systems have the node count to be able to run such benchmarks, but are not optimized or even capable of running them. Having these systems run these large calculations in a sustained way, and performing, is what separates a bunch of nodes together in a data center from an actual cluster that is able to run a benchmark like HPL or HPCG.
To sustain 70 - 80% of peak performance across hundreds of thousands of cores, you need a real low-diameter, high-bandwidth, low-latency fabric and a balanced memory subsystem, running on a system w almost no failures or network issues. A loosely-coupled cluster with an oversubscribed fat-tree will 'run Linpack' and then post an Rmax that's a small fraction of its naive peak.
Also, have a look at the Green500, and the systems there. This is not about bragging rights vendors, this is about placing commodity hardware, tuning it, and bringing it up to health in a way that squeezes all of that last performance possible out of the clusters on those lists. That's the opposite of vendor flexing - it's a craft that you cannot see in a simple node count, as some have been comparing here.
If you ever worked on this field, and with the vendors at this scale, you would know. Its not easy, its actually very hard.
... and imagine you need to deploy this, systems at this scale, w technologies that are sometimes just emerging and sometimes even need proper field testing * every 6 months * to be able to reach the scale and stability to land on these lists.