[Pw_forum] Do you think Intel I7 series could improve the parallel efficiency

[Axel Kohlmeyer]

On Wed, 2009-03-25 at 22:51 +0800, vega lew wrote:
> Dear sir,
> 
> You answer is quite helpful to me. Thank you very much. Actully, the
> speed of calculation for a large system is more 
> important for us. So I think the bandwidth is the key issue.
> 
> could I recognize the bandwidth you mentioned as the FSB (Front system
> bus) of the montherboard and the frequency of memory such as 800MHz or
> 1066 MHz and so on?

not really. you can see the bandwidth reliably from running the 
stream benchmark. those numbers do - of course - exist, but are
currently under NDA, so nobody can talk about it until the end 
of next week, IIRC.

from what is public already i can tell you, that the architecture 
of nehalem EP also requires that you pay great care as to where
memory modules are plugged in. good mainboards will have memory
slots in multiples of three. by placing memory modules in the wrong
slots, you can reduce the bandwidth by a factor of three. ;)

as with any new architecture, i would also expect that you'll have
expect a significant amount of problems with mainboard, bios, drivers
etc. and thus you should make sure that you have staff able to deal
with it.

axel

> thank you for your reply
> 
> vega
> 
> On Wed, Mar 25, 2009 at 8:45 PM, Axel Kohlmeyer
> <akohlmey at cmm.chem.upenn.edu> wrote:
>         On Wed, 2009-03-25 at 19:30 +0800, vega lew wrote:
>         > Dear all,
>         >
>         > Is there someone perform QE on intel I7 platform? Do you
>         think
>         > parallelzation QE could benefit from the QPI technology of
>         intel I7
>         > series very much?
>         
>         
>         the integrated memory controller and parallelization have very
>         little connection directly. please don't "believe" in
>         buzzwords.
>         
>         what _will_ help codes like Q-E in general is the greatly
>         enhanced
>         memory bandwidth, particularly the for larger systems. for
>         smaller
>         systems that mostly fit into the cache, the gains will be much
>         smaller.
>         the floating point unit of those cpus is essentially the same
>         as in
>         the current xeon processors.
>         since the various tests posted on the list here demonstrated
>         that
>         (some of) Q-E's parallelization schemes are very much affected
>         by
>         insufficient memory bandwidth, there will be a gain. however,
>         those
>         CPUs will also have a different cache architecture, which may
>         in
>         turn chew up some of the benefits, particularly for smaller
>         problems.
>         
>         cheers,
>           axel.
>         
>         
>         
>         >
>         > vega
>         >
>         > --
>         >
>         ==================================================================================
>         > Vega Lew ( weijia liu)
>         > PH.D Candidate in Chemical Engineering
>         > State Key Laboratory of Materials-oriented Chemical
>         Engineering
>         > College of Chemistry and Chemical Engineering
>         > Nanjing University of Technology, 210009, Nanjing, Jiangsu,
>         China
>         >
>         ******************************************************************************************************************
>         > Email: vegalew at gmail.com
>         > Office: Room A705, Technical Innovation Building, Xinmofan
>         Road 5#,
>         > Nanjing, Jiangsu, China
>         >
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>         --
>         =======================================================================
>         Axel Kohlmeyer   akohlmey at cmm.chem.upenn.edu
>         http://www.cmm.upenn.edu
>           Center for Molecular Modeling   --   University of
>         Pennsylvania
>         Department of Chemistry, 231 S.34th Street, Philadelphia, PA
>         19104-6323
>         tel: 1-215-898-1582,  fax: 1-215-573-6233,  office-tel:
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>         better idiot.
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> 
> 
> -- 
> ==================================================================================
> Vega Lew ( weijia liu)
> PH.D Candidate in Chemical Engineering
> State Key Laboratory of Materials-oriented Chemical Engineering
> College of Chemistry and Chemical Engineering
> Nanjing University of Technology, 210009, Nanjing, Jiangsu, China
> ******************************************************************************************************************
> Email: vegalew at gmail.com
> Office: Room A705, Technical Innovation Building, Xinmofan Road 5#,
> Nanjing, Jiangsu, China  
> ****************************************************************************************************************** 
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-- 
=======================================================================
Axel Kohlmeyer   akohlmey at cmm.chem.upenn.edu   http://www.cmm.upenn.edu
   Center for Molecular Modeling   --   University of Pennsylvania
Department of Chemistry, 231 S.34th Street, Philadelphia, PA 19104-6323
tel: 1-215-898-1582,  fax: 1-215-573-6233,  office-tel: 1-215-898-5425
=======================================================================
If you make something idiot-proof, the universe creates a better idiot.