[Beowulf] Woodcrest Memory bandwidth

sNAAPS eLYK 3lucid at gmail.com
Mon Aug 14 21:21:47 EDT 2006


Pardon my commenting on a discussion that's a little over my head, but
if I understand the architechtural differences between Opteron and
Pentium/Xeon, wouldn't the latency difference between them be
attributed at least in part to the on-die memory controller?

On 8/14/06, Stuart Midgley <sdm900 at gmail.com> wrote:
> actually, latency determines bandwidth more than memory speed...  see
> my rant(?) from a little over a year ago
>
> http://www.beowulf.org/archive/2005-July/013294.html
>
> prefetch etc. help, but the limiting factor is still latency.  Hence
> the opterons have significantly higher real memory bandwidth (their
> latency is about 1/3 that of xeons/p4's etc).  If you look at the
> ia64's then they have even high latency again, but they can have a
> huge number of outstanding loads (from memory its >80), so their
> effective bandwidth is high.
>
> Stu.
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