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The #1 cluster on the top 500 list would like to have a chat. Actually it looks like it's just the opposite of what you describe. Fujitsu build a CPU that's v

by sliken 6y ago

The #1 cluster on the top 500 list would like to have a chat. Actually it looks like it's just the opposite of what you describe. Fujitsu build a CPU that's very good at running a wide variety of applications. Unlike x86-64's that need accelerators for good FP or memory bandwidth per node, the A64FX does not need CUDA applications. Plain old fortran is just fine. Keep in mind the $40k includes support for porting applications, it doesn't mean that if you want 1000 of them that you'll have to pay $20k each.

fock 6y ago
yes, because running on the whole number #1 cluster is just recompiling your non-trivial software. no, it's not (just take a look at QuantumEspresso, which is widely used, not too bad, but does not scale tooo god with non-Fortran and QE experts testing). And as I said, this is a fine price, I just doubt that it's worth anyones attention who is not building an upper 6-figures to some millions cluster. And unless you actually port your application with Fujitsu (which incurs also personell cost) to take advantage of the arch, you will just fare better if you buy a bog-standard EPYC or even Skylake-Refresh, which "just works the same way it did before"©
- sliken 6y ago
  Not so sure, many of the impressive A64FX numbers were published with no source code changes. Even large complex codes like WRF (a weather simulator) "just works" and was faster than a dual socket Xeon 8168 (each Xeon 8168 is $5680 each list). For another F90 benchmark (Himeno) they got 4 times faster than a dual Xeon 8168 AND 1.1x faster than a Tesla V100 running the CUDA version of the same benchmark. IMO that's pretty amazing, no source code changes and you get BETTER than GPU performance without having to rewrite your code. So sure a standard Epyc or Skylake refresh will run your code and "just work", the a64fx opens up the possibility of significant performance upgrades with no source code changes. If your code isn't currently rewritten for CUDA getting 10x the bandwidth and 4x the CPU performance would be really attractive.

by sliken 6y ago

fock 6y ago

yes, because running on the whole number #1 cluster is just recompiling your non-trivial software. no, it's not (just take a look at QuantumEspresso, which is widely used, not too bad, but does not scale tooo god with non-Fortran and QE experts testing). And as I said, this is a fine price, I just doubt that it's worth anyones attention who is not building an upper 6-figures to some millions cluster. And unless you actually port your application with Fujitsu (which incurs also personell cost) to take advantage of the arch, you will just fare better if you buy a bog-standard EPYC or even Skylake-Refresh, which "just works the same way it did before"©

sliken 6y ago
Not so sure, many of the impressive A64FX numbers were published with no source code changes. Even large complex codes like WRF (a weather simulator) "just works" and was faster than a dual socket Xeon 8168 (each Xeon 8168 is $5680 each list). For another F90 benchmark (Himeno) they got 4 times faster than a dual Xeon 8168 AND 1.1x faster than a Tesla V100 running the CUDA version of the same benchmark. IMO that's pretty amazing, no source code changes and you get BETTER than GPU performance without having to rewrite your code. So sure a standard Epyc or Skylake refresh will run your code and "just work", the a64fx opens up the possibility of significant performance upgrades with no source code changes. If your code isn't currently rewritten for CUDA getting 10x the bandwidth and 4x the CPU performance would be really attractive.