Oh, and while you are at it. DO a bit of investigation on how the FVCOM model is optimised for use with AVX vectorisation. Hardware and clock speeds alone don't cut it.
On 16 February 2018 at 09:39, John Hearns <hear...@googlemail.com> wrote: > Ted, > I would go for the more modern system. you say yourself the first system > is two years old. In one or two years it will be out of warranty, and if a > component breaks you will have to decide to buy that component or just junk > they system. > > > Actually, having said that you should look at the FVCOM model and see how > well it scales on a multi-core system. > Intel are increasign core counts, but not clock speeds. PAradoxically in > the past you used to be able to get dual-core parts at over 3Ghz, which > don;t have many cores competing for bandwith to RAM. > The counter example to this is Skylake which has more channels to RAM, > makign for a more balannced system. > > I would go for a Skylake system, populate all the DIMM channels, and quite > honestly forget about runnign between two systems unless the size of your > models needs this. > Our latest Skylakes have 192Gbuytes of RAM for that reason. Int he last > generation this would sound like an unusual amount of RAM, but it makes > sense in the Skylake generation. > > > > > > > > > > On 15 February 2018 at 14:20, Tad Slawecki <tslawe...@limno.com> wrote: > >> >> Hello, list - >> >> We are at a point where we'd like to explore a tiny cluster of two >> systems to speed up execution of the FVCOM circulation model. We already >> have a two-year-old system with two 14-core CPUs (Xeon E-2680), and I have >> budget to purchase another system at this point, which we plan to directly >> connect via Infiniband. Should I buy an exact match, or go with the most my >> budget can handle (for example 2xXeon Gold 1630, 16-cores) under the >> assumption that the two-system cluster will operate at about the same speed >> *and* I can reap the benefits of the added performance when running smaller >> simulations independently? >> >> Our list owner already provided some thoughts: >> >> > I've always preferred homgenous clusters, but what you say is, >> > I think, quite plausible. The issue you will have though is >> > ensuring that the application is built for the earliest of the >> > architectures so you don't end up using instructions for a newer >> > CPU on the older one (which would result in illegal instruction >> > crashes). >> > >> > But there may be other gotchas that others think of! >> >> Thank you ... >> >> Tad >> _______________________________________________ >> Beowulf mailing list, Beowulf@beowulf.org sponsored by Penguin Computing >> To change your subscription (digest mode or unsubscribe) visit >> http://www.beowulf.org/mailman/listinfo/beowulf >> > >
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