<div dir="ltr">Hi Pierre,<div>I tried to combine openMP with MPI as you mentioned above when I do vibrational analysis. I required 6 MPI threads and got 6 output files named as *-r-number.out, however in each file it printed that:</div><div><div class="prettyprint" style="background-color: rgb(250, 250, 250); border-color: rgb(187, 187, 187); border-style: solid; border-width: 1px; overflow-wrap: break-word;"><code class="prettyprint"><div class="subprettyprint"><div class="subprettyprint"> GLOBAL| Total number of message passing processes 1</div><div class="subprettyprint"> GLOBAL| Number of threads for this process 1</div><div class="subprettyprint"> GLOBAL| This output is from process 0</div></div></code></div>also I used 'top' command and found that only 6 cores were busy. </div><div>I use 2 x 24 core processor, and set:</div><div><div class="prettyprint" style="background-color: rgb(250, 250, 250); border-color: rgb(187, 187, 187); border-style: solid; border-width: 1px; overflow-wrap: break-word;"><code class="prettyprint"><div class="subprettyprint"><div class="subprettyprint">export OMP_NUM_THREADS=8</div><div class="subprettyprint">mpirun -n 6 /lib/CP2K/cp2k/exe/local/cp2k.popt -i project.inp -o output.out</div></div></code></div>Any suggestion will be greatly appreciated..<br><br><br><br>在 2019年9月20日星期五 UTC+8下午10:45:55，Pierre Cazade写道：<blockquote class="gmail_quote" style="margin: 0;margin-left: 0.8ex;border-left: 1px #ccc solid;padding-left: 1ex;">
<div text="#000000" bgcolor="#FFFFFF">
Hello Nikhil,<br>
<br>
Withe command "mpirun -n 42 cp2k.pop -i inp.inp -o -out.out", you
are requesting 42 MPI threads and not 42 OpenMP threads. MPI usually
relies on replicated data which means that, for a poorly program
software, it will request a total amount of memory which the amount
of memory required by a scalar execution times the number of
threads. This can very quickly become problematic, in particular for
QM calculations. OpenMP, however relies on shared memory, the data
is normally not replicated but shared between threads and therefore,
in an ideal scenario, the amount of memory needed for 42 OpenMP
threads is the same as a single one.<br>
<br>
This might explains why you calculation freezes. You are out of
memory. On your workstation, you should only use the executable
"cp2k.ssmp" which is the OpenMP version. Then you don't need the
mpirun command:<br>
<br>
cp2k.ssmp -i inp.inp -o -out.out<br>
<br>
To control the number of OpenMP threads, set the env variable:
OMP_NUM_THREADS, e.g. in bash, export OMP_NUM_THREADS=48<br>
<br>
Now, if you need to balance between MPI and OpenMP, you should use
the executable named cp2k.psmp. Here is such an example:<br>
<br>
export OMP_NUM_THREADS=24<br>
mpirun -n 2 cp2k.psmp -i inp.inp -o -out.out<br>
<br>
In this example, I am requesting two MPI threads and each of them
can use up to 24 OpenMP threads.<br>
<br>
Hope this clarifies things for you.<br>
<br>
Regards,<br>
Pierre<br>
<br>
<div>On 20/09/2019 14:09, Nikhil Maroli
wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">Dear all,
<div><br>
</div>
<div>I have installed all the versions of CP2K in my workstation
with 2 x 12 core processor, total thread=48</div>
<div><br>
</div>
<div>I wanted to run cp2k in parallel using 42 threads, can
anyone share the commands that i can use.</div>
<div><br>
</div>
<div>I have tried </div>
<div><br>
</div>
<div>mpirun -n 42 cp2k.pop -i inp.inp -o -out.out</div>
<div><br>
</div>
<div>After this command there is a rise in memory to 100 % and
the whole system freezes. (i have 128GB ram).</div>
<div><br>
</div>
<div>Any suggestion will be greatly appreciated,</div>
</div>
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</blockquote>
<br>
<pre cols="72">--
Dr Pierre Cazade, PhD
AD3-023, Bernal Institute,
University of Limerick,
Plassey Park Road,
Castletroy, co. Limerick,
Ireland</pre>
</div>
</blockquote></div></div>