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