[Beowulf] performance tweaks and optimum memory configs for a Nehalem
hahn at mcmaster.ca
Sat Aug 8 15:47:47 PDT 2009
> Is it a bad mistake to configure a Nehalem (2 sockets quad core giving
> a total of 8 cores; E5520) with 16 GB RAM (4 DIMMs of 4GB each)? I
there's no ambiguity here: unpopulated channels decrease bandwidth
and/or concurrency. (does anyone know whether nehalem can "ungang"
memory channels like opteron can? it would be fascinating to see
benchmarks showing a benefit to higher memory concurrency for a
> Our code requirements dictate 2 GB / core is enough. Should I be
> paying for the additional RAM to make it 24 GB?
ram is, historically and relatively, cheap. otoh, can your code get
by with 1.5G/core? actually, I tend to see some association with
smallish memory footprints (2G/core is definitely not large) with
cache-friendliness. this would argue that the higher bandwidth may
not make much difference to your code...
regards, mark hahn.
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