[Beowulf] Single threaded memory bandwidth compared between Nehalem-EP and Westmere-EX

[Chris Samuel]

On Fri, 18 Oct 2013 12:32:00 PM Reuti wrote:

> Hi,
> 
> Am 18.10.2013 um 05:34 schrieb Christopher Samuel:
> > 
> > We've got a group who bought themselves a 16 core 1.5TB Westmere-EX
> > system and are getting what they consider to be poor memory bandwidth
> > compared to an older 8 core Nehalem-EP system.
> 
> Can you specify the CPUs in question?

X5550 for Nehalem-EP
E7-8837 for Westmere-EX

> > Same CPU clock speed (2.6GHz), same memory speed (1067MHz), but about
> > half the memory bandwidth (single threaded). I've run my own tests
> > with the Stream benchmark and can confirm the same.
> 
> Is the speed limited by the memory chips or the mainboard, or the population
> on the mainboard (i.e. often the speed drops when all DIMM banks are used).

I suspect not for mainboard, this is a IBM x3690 X5's and we've also got a 
quad socket SGI Altix UV10 with 1TB of RAM which shows pretty much the same 
bandwidth.

cheers,
Chris
-- 
 Christopher Samuel        Senior Systems Administrator
 VLSCI - Victorian Life Sciences Computation Initiative
 Email: samuel at unimelb.edu.au Phone: +61 (0)3 903 55545
 http://www.vlsci.org.au/      http://twitter.com/vlsci