Dear Meep users,
I want to buy a new computer (or a small workstation if that will be the
best deal) for running numerical calculation - among which Meep. Maybe with
two processors, but first I want to get some information and orient myself
on the various options: if possible, I would like to get some hints on
which may be the best chip (given some reasonable price constraints) for
running Meep-MPI. I plan to run models with size of a couple of Gb.

I have asked around, and someone told me that, since a FDTD code needs to
read the whole field from RAM at every cycle, then the most important
consideration for a fast system is actually RAM speed; and second the
processor should be somehow adapted to the speed of the memory, requesting
RAM data at exactly the same speed at which RAM is able to supply them: if
the processor asks data more quickly than that the result is worse
performance. Can someone confirm/comment on this? 

The second consideration, that I saw in a past thread on Meep-discuss
is that MPI is not designed in particular for multicore systems, that have
shared memory, but for multiprocessor systems in which each processor has
its own memory (or a separate connection to the memory, I have not
understood well). In fact for the about 1 Gb model that I am running now,
using OpenMPI (the one that I found pre-installed on the Macbook Pro I own:
I haven't yet checked how things work if I install the current version of
OpenMPI) on a Core2 duo, I get a very small performance improvement with
respect to the single processor Meep (each step runs in about 0.75 seconds
with two processes rather than 0.80 seconds on the single-processor
version). I read in that thread that Corei7 processors should be
substantially better from that point of view. Can someone comment? Should
one go for a Corei7 or a Xeon processor?

Thanks in advance,


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