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That looks like a memory cache issue. What is the memory configuration for desktop versus laptop? There may be more than one cache involved (disk cache, Ram cache, CPU cache).</div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Dune-devel <dune-devel-bounces@lists.dune-project.org> on behalf of Flemisch, Bernd <bernd.flemisch@iws.uni-stuttgart.de><br>
<b>Sent:</b> Tuesday, December 15, 2020 4:59 AM<br>
<b>To:</b> dune-devel@lists.dune-project.org <dune-devel@lists.dune-project.org><br>
<b>Subject:</b> Re: [Dune-devel] Long MPI startup</font>
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<p>Just to let you know that you're not alone. I experience the same issue on my rather new laptop with Ubuntu 20.04 and 20.10. Both for OpenMPI and MPICH. And only for the first of several consecutive runs, try</p>
<p>./a.out && ./a.out && ./a.out</p>
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<p>I don't have that problem on my desktop which still runs on openSUSE 15.0. Kind of hard to bisect this.</p>
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<p>Kind regards</p>
<p>Bernd</p>
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<span style="font-family:"Courier New",monospace; font-size:10pt">_________________________________________________________________</span><br>
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<span style="font-family:"Courier New",monospace; font-size:10pt">Bernd Flemisch</span><br>
<span style="font-family:"Courier New",monospace; font-size:10pt">IWS, Universität Stuttgart phone: +49 711 685 69162</span><br>
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<a href="http://www.iws.uni-stuttgart.de/en/lh2/" class="x_x_OWAAutoLink" title="http://www.iws.uni-stuttgart.de/en/lh2/ Ctrl+Klicken oder tippen Sie, um dem Link zu folgen." id="LPNoLP">
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<div id="x_x_divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>Von:</b> Dune-devel <dune-devel-bounces@lists.dune-project.org> im Auftrag von Oliver Sander <oliver.sander@tu-dresden.de><br>
<b>Gesendet:</b> Dienstag, 15. Dezember 2020 11:34:48<br>
<b>An:</b> dune-devel@lists.dune-project.org<br>
<b>Betreff:</b> Re: [Dune-devel] Long MPI startup</font>
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<div class="x_PlainText">Hi Markus,<br>
<br>
thanks for your help. Indeed, your test program also requires<br>
about 2.5 seconds to terminate, so there really is nothing<br>
Dune-specific about it.<br>
<br>
It is still annoying though. My machine is a recent-ish ThinkPad Yoga,<br>
with 8 cores, running Debian Testing. I suppose I'll just have to<br>
suck it up.<br>
<br>
Best,<br>
Oliver<br>
<br>
On 15.12.20 10:19, Markus Blatt wrote:<br>
> Hi,<br>
> <br>
> <br>
> On Fri, Dec 11, 2020 at 12:19:56PM +0100, Oliver Sander wrote:<br>
>><br>
>> I recently noticed that on my system (current Debian testing), the call to<br>
>><br>
>> MPIHelper::instance(argc, argv);<br>
>><br>
>> takes between 2 and 3 seconds to complete. This seems like a long time to me.<br>
>> Is it to be expected? Or is there a bug somewhere?<br>
> <br>
> I don't think that we do anything specical during startup (besides calling<br>
> MPI_Init). Hence I doubt that this is a Dune problem.<br>
> <br>
> Maybe you cound try a minimal MPI program to compare?<br>
> <br>
> #include <mpi.h><br>
> #include <iosteam><br>
> <br>
> int main(int argc, char** argv){<br>
> MPI_Init(&argc, argv);<br>
> int size, rank;<br>
> MPI_Comm_size(&size, MPI_COMM_WORLD);<br>
> MPI_Comm_rank(&rank, MPI_COMM_WORLD);<br>
> //Above should be all that DUNE does<br>
> std::cout<<"Hi, I am rank "<<rank<<" of "<<size<<"."<<std::endl;<br>
> MPI_Finalize();<br>
> return 0;<br>
> }<br>
> <br>
> BTW on my multicore machine (32 cores) it takes some time, too.<br>
> Mabe you have a new machine? What MPI?<br>
> <br>
> HTH,<br>
> <br>
> Markus<br>
> <br>
<br>
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