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Comment by dibanez | Hacker News Reader

Its essentially a matter of realistic benchmark acceptance. Right now machines are compared by how well they run this benchmark called LINPACK, which has been criticized for being non-representative of real science codes. As mentioned here [1], China's new system only achieved 0.3% of its peak flops on a slightly more realistic benchmark, HPCG.

[1] http://www.hpcwire.com/2016/06/19/china-125-petaflops-sunway...

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While Sunway TaihuLight has weak HPCG performance, 0.3% number should be understood in context. Tianhe-2 (#2 system) scores 1.1%, and Titan (#3, US #1 system) scores 1.2% for HPCG. So Sunway TaihuLight is 3~4x worse for HPCG compared to other top systems.

Note that K computer (#5 system, Japan) scores 4.9% for HPCG. So Tianhe-2 and Titan are again 4x worse for HPCG compared to systems which score best for HPCG.

Why does the Sunway TaihuLight have bad HPCG performance? I suspect it has to do with memory bandwidth needed to serve 260C on the same chip?

Yes, it's memory and interconnect.

I don't think it's as simple as LINPACK bad, HPCG good. LINPACK is representative for some workloads, when compute dominates. HPCG aims to balance compute and memory. There is Graph500, if memory dominates for your workload.

By the way, K computer is #1 in Graph500.

http://www.graph500.org/

The interconnect on the Sunway TaihuLight seems to be standard Infiniband, from reading other articles about the system.

I was wondering about third-party benchmarks. As far as I know, the Top500 is pure self-report, and this is a big national-prestige thing...

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