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<p>What virtual machine (Virtual Box, VMware, etc. [1])? Seems to
matter according to [2,3].</p>
<p><br>
</p>
<p>Since a virtual machine tends to be an operating system running
on top of another operating system (OS), there will most likely be
a performance loss to your calculations [4]. Perhaps the
calculation will run slower [disk caching due to lack of random
access memory (RAM), CPU sharing between both OS) or structures
that can be calculated could be limited by the loss of free RAM
(two OS using RAM instead of just one OS + RAM used by virtual
machine software].<br>
</p>
<p><br>
</p>
<p>TiC case is fine for first learning mpi parallel but is known
that it can be slower than just doing a serial calculation for it
as it is too small a case (e.g., to few nonequivalent atomic
positions) [5,6].</p>
<p><br>
</p>
<p>Your statement below "... <font color="#009900">calculations
take longer than in series</font> ..." seems to confirm this.<br>
</p>
<p><br>
</p>
<p>"... <font color="#ff6600">one processor for the variable <font
color="#993399">OMP_THREAD</font> (instead of 20 cores)</font>
..." <- Don't confuse a thread and a core, they should be
different [7,8,9]. For example, look at the specifications for an
i7-8700K processor [10] which shows that Intel processor has # of
cores as 6 and # of threads as 12.<br>
</p>
<p><br>
</p>
<p>Is <font color="#993399">OMP_THREAD</font> a special variable
particular to your system? If not, you might want to check your
.bashrc (within the block created by userconfig_lapw) and the
WIEN2k 19.1 UG (section "5.5.3 How to use WIEN2k as a parallel
program" on page 86) [11] as a different environmental variable
might be needed.<br>
</p>
<p><br>
</p>
<p>username@computername:~$ grep THREAD ~/.bashrc<br>
export <font color="#993399">OMP_NUM_THREADS</font>=1<br>
</p>
<p><br>
</p>
<p>[1]
<a class="moz-txt-link-freetext" href="https://en.wikipedia.org/wiki/Virtual_machine#Full_virtualization">https://en.wikipedia.org/wiki/Virtual_machine#Full_virtualization</a><br>
</p>
<p>[2]
<a class="moz-txt-link-freetext" href="https://superuser.com/questions/1035010/what-is-the-performance-difference-of-a-virtual-machine-vs-the-physical-host">https://superuser.com/questions/1035010/what-is-the-performance-difference-of-a-virtual-machine-vs-the-physical-host</a><br>
</p>
<p>[3]
<a class="moz-txt-link-freetext" href="https://www.researchgate.net/post/Why_there_is_a_performance_variation_between_physical_machine_and_virtual_machine_with_same_number_of_cores_and_memory">https://www.researchgate.net/post/Why_there_is_a_performance_variation_between_physical_machine_and_virtual_machine_with_same_number_of_cores_and_memory</a><br>
</p>
<p>[4]
<a class="moz-txt-link-freetext" href="https://hetmanrecovery.com/recovery_news/how-to-speed-up-the-operation-of-a-virtual-machine.htm">https://hetmanrecovery.com/recovery_news/how-to-speed-up-the-operation-of-a-virtual-machine.htm</a><br>
</p>
<p>[5]
<a class="moz-txt-link-freetext" href="https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg05622.html">https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg05622.html</a></p>
<p>[6]
<a class="moz-txt-link-freetext" href="https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg02976.html">https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg02976.html</a><br>
</p>
<p>[7]
<a class="moz-txt-link-freetext" href="https://bitsum.com/tips-and-tweaks/what-is-the-difference-between-a-thread-and-a-core/">https://bitsum.com/tips-and-tweaks/what-is-the-difference-between-a-thread-and-a-core/</a></p>
<p>[8]
<a class="moz-txt-link-freetext" href="https://www.intel.com/content/www/us/en/architecture-and-technology/hyper-threading/hyper-threading-technology.html">https://www.intel.com/content/www/us/en/architecture-and-technology/hyper-threading/hyper-threading-technology.html</a></p>
<p>[9]
<a class="moz-txt-link-freetext" href="https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg08702.html">https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg08702.html</a><br>
</p>
<p>[10]
<a class="moz-txt-link-freetext" href="https://ark.intel.com/content/www/us/en/ark/products/126684/intel-core-i7-8700k-processor-12m-cache-up-to-4-70-ghz.html">https://ark.intel.com/content/www/us/en/ark/products/126684/intel-core-i7-8700k-processor-12m-cache-up-to-4-70-ghz.html</a></p>
<p>[11]
<a class="moz-txt-link-freetext" href="http://susi.theochem.tuwien.ac.at/reg_user/textbooks/usersguide.pdf">http://susi.theochem.tuwien.ac.at/reg_user/textbooks/usersguide.pdf</a><br>
</p>
<p><br>
</p>
<div class="moz-cite-prefix">On 8/19/2019 10:00 PM, Israel Omar
Perez Lopez wrote:<br>
</div>
<blockquote type="cite"
cite="mid:BN7PR07MB5090E98D7695D6B99A5B71088AAB0@BN7PR07MB5090.namprd07.prod.outlook.com">
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<p style="margin-top:0;margin-bottom:0">Dear mailing list</p>
<p style="margin-top:0;margin-bottom:0"><br>
</p>
<p style="margin-top:0;margin-bottom:0">I have a virtual machine
with 20 cores running in linux mint (linux recognizes that the
computer has 20 cores divided in two nodes 10 each, however,
there is only one physical node). How can I use Wien2k to do
parallel calculations in a virtual machine so the
parallelization uses the 20 cores. As far as I know, wien2k
19.1 has three modes of parallelization: MPI, k-point and OMP
(according to the UG only for computers with less than 8
cores). I have already installed intel parallel studio 2019
and wien2k but when I do the userconfig the system only
detects <font color="#ff6600">one processor for the variable
<font color="#993399">OMP_THREAD</font> (instead of 20
cores)</font>. Since it is only one machine, what is the
best configuration in the .machines file to use the 20 cores?
Based on the UG I have tried three configurations for TiC in
.machines: 1) localhost:20, 2) MPI parallelization implemented
as: localhost, localhost, ....localhost 20 times, and 3)
k-point implemented as:
<br>
</p>
<p style="margin-top:0;margin-bottom:0">localhost</p>
<p style="margin-top:0;margin-bottom:0">localhost</p>
<p style="margin-top:0;margin-bottom:0">....</p>
<p style="margin-top:0;margin-bottom:0">20 times</p>
<p style="margin-top:0;margin-bottom:0"><br>
</p>
<p style="margin-top:0;margin-bottom:0">For the first and second
case, the computations do not stop, it does not even compute
lapw0, so I have to cancel the job with cancel_lapw. For the
third case the calculations are carried out, but it seems that
the 20 cores do not work at the same time, they work one after
another and at the end, the<font color="#009900"> calculations
take longer than in series</font>. I checked this with
testpara1.<br>
</p>
<p style="margin-top:0;margin-bottom:0"><br>
</p>
<p style="margin-top:0;margin-bottom:0">I would be glad if you
could give a helpful comment on how to use the 20 cores in
this machine.</p>
<p style="margin-top:0;margin-bottom:0"><br>
Regards</p>
<p style="margin-top:0;margin-bottom:0"><br>
</p>
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<div><font size="2">Dr. Israel Pérez</font>
<div><font size="2"><br>
</font></div>
<div>
<div>
<p class="MsoNormal" style="text-align:justify"><font
size="2">Institute of Engineering and
Technology</font></p>
<p class="MsoNormal" style="text-align:justify"><font
size="2">Department of Physics and
Mathematics, </font></p>
<p class="MsoNormal" style="text-align:justify"><font
size="2">Universidad Autónoma de Ciudad
Juárez </font></p>
<p class="MsoNormal"><font size="2">Av. del Charro
450 Nte., Col. Partido Romero, </font></p>
<p class="MsoNormal"><font size="2">Ciudad Juárez,
Juarez Chihuahua. Mexico C. P. 32310</font></p>
<p class="MsoNormal"><font size="2">Tel: +52 (656)
688 4887</font></p>
<p class="MsoNormal"><font size="2"><br>
</font></p>
<p class="MsoNormal"><font size="2">National
Council of Science and Technology</font></p>
<div>
<p class="MsoNormal" style="text-align:justify"><font
size="2">Insurgentes Sur No. 1582, </font></p>
<p class="MsoNormal" style="text-align:justify"><font
size="2">Col. Crédito Constructor, C.P.
03940</font></p>
<p class="MsoNormal" style="text-align:justify"><font
size="2">Del. Benito Juárez, México D. F.</font></p>
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</div>
</blockquote>
<br>
<blockquote type="cite"
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