<div dir="ltr">Dear Prof. Blaha,<div><br></div><div style> Just for curiosity, what processor did you buy ?</div><div style> Is the Xeon family better than the i7 one for WIEN2k calculations ?</div><div style> All the best,</div>
<div style> Luis</div></div><div class="gmail_extra"><br><br><div class="gmail_quote">2013/9/11 Peter Blaha <span dir="ltr"><<a href="mailto:pblaha@theochem.tuwien.ac.at" target="_blank">pblaha@theochem.tuwien.ac.at</a>></span><br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">I don't know what "latest" means. We use the latest one installed on our supercomputers (4.1.1.036)<br>
<br>
I have not seen any significant change with mpi in the last years.<br>
<br>
PS: I just got info that we have now a new ifort available for download ...<div class="HOEnZb"><div class="h5"><br>
<br>
On 09/11/2013 05:00 PM, Laurence Marks wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Thanks.<br>
<br>
One thing I will add/ask concerning the parallelization, the latest<br>
impi seems to be substantially better -- have you tried it? I have not<br>
just noticed this with Wien2k, but I am told that others have seen<br>
improvements in other codes.<br>
<br>
On Wed, Sep 11, 2013 at 9:42 AM, Peter Blaha<br>
<<a href="mailto:pblaha@theochem.tuwien.ac.at" target="_blank">pblaha@theochem.tuwien.ac.at</a>> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Before buying a couple of new computers, I was asking myself the same<br>
question and discussed this with some people of our computing departments.<br>
<br>
The conclusions:<br>
a) potentially very good, but in practice very questionable, because for<br>
most application you cannot get out the real speed (10 times faster than<br>
an Intel I7). This is true, even for many lapack/mkl subroutines where<br>
it "should" work better.<br>
They told me to "wait", until the mkl becomes better (hopefully). I'm<br>
not too optimistic, when you see how badly the mkl-parallelization of<br>
multicore machines is working (2 cores is very good, but 4 or more is<br>
already very bad).<br>
<br>
b) The nature of our problem (big eigenvalue problem): A "fast<br>
processor" is useful only for large problems --> large memory.<br>
You can buy Phi coprocessors now with quite some large memory, but then<br>
they are terrible expensive (and 5 "normal" PCs are faster and cheaper)<br>
<br>
c) the hardware design has a VERY slow communication between main-memory<br>
and Phi-memory. This makes also parallelization over several PHI-nodes<br>
via mpi not really possible (if you need any significant data transfer,<br>
like for an eigenvalue problem).<br>
<br>
Thus I did not buy it.<br>
<br>
However, if anybody has access and time to try out WIEN2k on PHis, I'd<br>
would be very interested in getting feedback. (Maybe these<br>
computer-people were not good enough ....)<br>
<br>
PS: I know from G.Kresse that they had some time ago (maybe 2 years ?)<br>
an expert from NVIDIA with them. After 2 weeks of porting VASP to these<br>
GPUs by this expert, VASP on the GPU was "almost as fast" as on an Intel<br>
I7 processor.<br>
<br>
<br>
On 09/11/2013 04:16 PM, Laurence Marks wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Anyone know if these will be viable with Wien2k (mpi, i.e. large problems)?<br>
<br>
</blockquote>
<br>
--<br>
<br>
P.Blaha<br>
------------------------------<u></u>------------------------------<u></u>--------------<br>
Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna<br>
Phone: <a href="tel:%2B43-1-58801-165300" value="+43158801165300" target="_blank">+43-1-58801-165300</a> FAX: <a href="tel:%2B43-1-58801-165982" value="+43158801165982" target="_blank">+43-1-58801-165982</a><br>
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<br>
-- <br>
<br>
P.Blaha<br>
------------------------------<u></u>------------------------------<u></u>--------------<br>
Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna<br>
Phone: <a href="tel:%2B43-1-58801-165300" value="+43158801165300" target="_blank">+43-1-58801-165300</a> FAX: <a href="tel:%2B43-1-58801-165982" value="+43158801165982" target="_blank">+43-1-58801-165982</a><br>
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