[Beowulf] General thoughts on Xeon 56xx versus E5 series?

Igor Kozin i.n.kozin at googlemail.com
Fri Sep 14 04:00:06 PDT 2012

if memory bandwidth is your concern then there are models which boost
it quite significantly. e.g.
probably very few codes are going to benefit from AVX without extra
efforts but BW is a clear win.
i'm seeing a good speed up on some applications which can be
attributed to higher BW.

On 13 September 2012 15:48, Orion Poplawski <orion at cora.nwra.com> wrote:
> On 09/13/2012 08:09 AM, holway at th.physik.uni-frankfurt.de wrote:
>>> Any general thought out there on Xeon 56xx versus E5 performance wise?
>> We were comparing the performance of an older AMD with a newer AMD a while
>> ago and found that the newer AMDs floating point performance was
>> significantly reduced.
>> It turned out that the kernel did not yet support AVX or FMA4 or some
>> other new fancy bit of register blah blah so it reverted to some
>> compatibility support for floating point operations. (I am not a kernel
>> dev :)
>> If your going to play with newer processors you have to make sure your
>> kernel supports all the functions of that CPU. Kernel development can be a
>> little way behind on mainstream releases.
>> Ta,
>> Andrew
> Thanks for the reminder of kernel support.  RedHat states that RHEL5.7 should
> support the E5 processors, so hopefully that means supporting the new
> instructions.
> It seems the question before us is core scaling versus raw MHz.  I've seen
> many codes saturate the memory bandwidth before filling all of the cores and
> it seems you have a trade off between MHz and cores these days at a given
> price point.  But perhaps that doesn't even matter if you're memory bandwidth
> limited anyways.
> --
> Orion Poplawski
> Technical Manager                     303-415-9701 x222
> NWRA, Boulder Office                  FAX: 303-415-9702
> 3380 Mitchell Lane                       orion at nwra.com
> Boulder, CO 80301                   http://www.nwra.com
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