On 09/13/2012 08:09 AM, hol...@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 or...@nwra.com Boulder, CO 80301 http://www.nwra.com _______________________________________________ Beowulf mailing list, Beowulf@beowulf.org sponsored by Penguin Computing To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
