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Hi Pratik,<br>
<br>
May I ask what kind of connection do you have between the two nodes
when you run in parallel? Is it Gigabit Ethernet or something else?<br>
<br>
I would like to do the same thing but now have to pause as your
experience.<br>
<br>
Thanks,<br>
Rolly <br>
<br>
<div class="moz-cite-prefix">On 05/25/2016 06:50 PM, PRATIK DAS
wrote:<br>
</div>
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cite="mid:CAEyNvDvPjbLAfBwjs35bF_Ms7F4ZKyEKU6h5A36yRSqaKH3KwQ@mail.gmail.com"
type="cite">
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<div>Dear QE users,<br>
</div>
I am not a new user of quantum espresso.
Previously I worked on a single machine of 4
core. I simply worked with mpi by 'mpirun -np
4', and the job was faster than a serial run.<br>
</div>
Now I have a 2 node cluster. Each node consists
of 2 processors of 12 core each. Hence I made a
hostfile(for a single node) by specifying <br>
"node1 slots=24".<br>
Now my command is <br>
</div>
"mpirun --hostfile my_hostfile -np 24 ph.x <<a
moz-do-not-send="true" href="http://input.in"
target="_blank">input.in</a>> output.out".
This run takes 9hours and 39 minutes.<br>
</div>
But when I want to use both nodes by<br>
</div>
"node1 slots=24<br>
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node2 slots=24"<br>
</div>
& command<br>
"mpirun --hostfile my_hostfile -np 48 ph.x <<a
moz-do-not-send="true" href="http://input.in"
target="_blank">input.in</a>> output.out -ni 6 -nk
2",<br>
</div>
It is taking too much time to complete the job. Even it is
now almost 26 hours over. 2nd q point calculation is going
on.<br>
<br>
</div>
NB: The job has only 4 q points.<br>
<br>
</div>
I have also seen this in pw.x run. In a single node, it is
taking only 2mins.<br>
Command: mpirun --hostfile my_hostfile -np 24 pw.x <<a
moz-do-not-send="true" href="http://input.in" target="_blank">input.in</a>>
output.out.<br>
<br>
But in case of both nodes, it is taking almost half an hour.<br>
<div>Command: mpirun --hostfile my_hostfile -np 48 pw.x <<a
moz-do-not-send="true" href="http://input.in"
target="_blank">input.in</a>> output.out<br>
<br>
</div>
<div>Can anyone suggest me that why the jobs running on 2 nodes
are slower than the jobs in single node?<br>
<br>
</div>
<div>Thanks in advance.<br>
<br>
<br>
</div>
<div>Regards<br>
</div>
Pratik Kumar Das
<div>
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<div><i><span style="color:rgb(0,0,255)"><b>Pratik
Kr. Das</b></span></i><br>
</div>
<span
style="background-color:rgb(224,102,102)"><span
style="color:rgb(106,168,79)"><span
style="background-color:rgb(224,102,102)"><span><span
style="background-color:rgb(204,204,204)"></span></span></span><span
style="color:rgb(11,83,148)"><span
style="background-color:rgb(255,255,255)">Research
Fellow<br>
</span></span></span></span></div>
<div><span style="color:rgb(11,83,148)"><span
style="background-color:rgb(255,255,255)">High Pressure and Temperature
Lab<br>
</span></span></div>
<span style="color:rgb(11,83,148)"><span
style="background-color:rgb(255,255,255)">Faculty
of Science<br>
</span></span></div>
<span style="color:rgb(11,83,148)"><span
style="background-color:rgb(255,255,255)">Jadavpur
University<br>
</span></span></div>
<span style="color:rgb(11,83,148)"><span
style="background-color:rgb(255,255,255)">Kolkata
700032<br>
</span></span></div>
<div><span style="background-color:rgb(224,102,102)"><span
style="color:rgb(106,168,79)"><span
style="background-color:rgb(255,255,255)"><span
style="color:rgb(11,83,148)"></span><span></span></span></span></span><br>
</div>
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</blockquote>
<br>
<pre class="moz-signature" cols="72">--
PhD. Research Fellow,
Dept. of Physics & Materials Science,
City University of Hong Kong
Tel: +852 3442 4000
Fax: +852 3442 0538</pre>
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