[Wien] Intel(R) Xeon Phi™ coprocessor

[Laurence Marks]

Thanks.

One thing I will add/ask concerning the parallelization, the latest
impi seems to be substantially better -- have you tried it? I have not
just noticed this with Wien2k, but I am told that others have seen
improvements in other codes.

On Wed, Sep 11, 2013 at 9:42 AM, Peter Blaha
<pblaha at theochem.tuwien.ac.at> wrote:
> Before buying a couple of new computers, I was asking myself the same
> question and discussed this with some people of our computing departments.
>
> The conclusions:
> a) potentially very good, but in practice very questionable, because for
> most application you cannot get out the real speed (10 times faster than
> an Intel I7). This is true, even for many lapack/mkl subroutines where
> it "should" work better.
> They told me to "wait", until the mkl becomes better (hopefully). I'm
> not too optimistic, when you see how badly the mkl-parallelization of
> multicore machines is working (2 cores is very good, but 4 or more is
> already very bad).
>
> b) The nature of our problem (big eigenvalue problem): A "fast
> processor" is useful only for large problems --> large memory.
> You can buy Phi coprocessors now with quite some large memory, but then
> they are terrible expensive (and 5 "normal" PCs are faster and cheaper)
>
> c) the hardware design has a VERY slow communication between main-memory
> and Phi-memory. This makes also parallelization over several PHI-nodes
> via mpi not really possible (if you need any significant data transfer,
> like for an eigenvalue problem).
>
> Thus I did not buy it.
>
> However, if anybody has access and time to try out WIEN2k on PHis, I'd
> would be very interested in getting feedback. (Maybe these
> computer-people were not good enough ....)
>
> PS: I know from G.Kresse that they had some time ago (maybe 2 years ?)
> an expert from NVIDIA with them. After 2 weeks of porting VASP to these
> GPUs by this expert, VASP on the GPU was "almost as fast" as on an Intel
> I7 processor.
>
>
> On 09/11/2013 04:16 PM, Laurence Marks wrote:
>> Anyone know if these will be viable with Wien2k (mpi, i.e. large problems)?
>>
>
> --
>
>                                        P.Blaha
> --------------------------------------------------------------------------
> Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
> Phone: +43-1-58801-165300             FAX: +43-1-58801-165982
> Email: blaha at theochem.tuwien.ac.at    WWW:
> http://info.tuwien.ac.at/theochem/
> --------------------------------------------------------------------------
> _______________________________________________
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
> SEARCH the MAILING-LIST at:  http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html



-- 
Professor Laurence Marks
Department of Materials Science and Engineering
Northwestern University
www.numis.northwestern.edu 1-847-491-3996
"Research is to see what everybody else has seen, and to think what
nobody else has thought"
Albert Szent-Gyorgi