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Hi Nicholas,</div>
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Assuming ParaView is using the same behavior as upstream hydra</div>
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<ul>
<li><span><code><code>-np 8</code> should launch 8 processes, 4 on each node<br>
</code></span></li><li><span><code>-np 4 should launch 4 processes, 2 on each node</code></span></li><li><span><code>To launch 4 processes on one node</code>, try <code>-hosts compute0:4,compute1:4 -np 4</code></span></li><li><span>The number 4 behind each host instructs hydra to assign the first 4 ranks to the host before moving on to another assignment, the default is 1. Hydra uses round-robin assignment policy</span></li></ul>
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<div><span>Hope it helps,</span></div>
<div><span><br>
</span></div>
<div><span>--</span></div>
<div><span>Hui<br>
</span></div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Nicholas Yue via discuss <discuss@mpich.org><br>
<b>Sent:</b> Friday, May 6, 2022 11:11 AM<br>
<b>To:</b> discuss@mpich.org <discuss@mpich.org><br>
<b>Cc:</b> Nicholas Yue <yue.nicholas@gmail.com><br>
<b>Subject:</b> [mpich-discuss] mpiexec : multi nodes and multi-cores questions</font>
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<div dir="ltr">Hi,<br>
<br>
I am using mpiexec from Paraview which from the `help` print out, indicates that it is derived from MPICH
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<div>```</div>
<div>Please see the intructions provided at<br>
<a href="http://wiki.mpich.org/mpich/index.php/Using_the_Hydra_Process_Manager">http://wiki.mpich.org/mpich/index.php/Using_the_Hydra_Process_Manager</a><br>
for further details<br>
</div>
<div>```</div>
<div><br>
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<div> so I thought I might ask some questions on this mailing list.<br>
<br>
I have set up a two node cluster, each compute node has 4 cores<br>
<br>
To fully utilise all the cores in both nodes, is this the correct way to launch pvserver ?<br>
<br>
```<br>
/shared/ParaView-5.10.1-osmesa-MPI-Linux-Python3.9-x86_64/bin/mpiexec -hosts compute0,compute1 -np 8 /shared/ParaView-5.10.1-osmesa-MPI-Linux-Python3.9-x86_64/bin/pvserver<br>
```</div>
<div><br>
If I change to `-np 4` would mpiexec use only compute0 or would it still run on both compute0 and compute1 but use only 2 cores of each node ?<br>
<br>
Cheers<br>
-- <br>
<div dir="ltr" class="x_gmail_signature">
<div dir="ltr">Nicholas Yue<br>
<a href="https://www.linkedin.com/in/nicholasyue/" target="_blank">https://www.linkedin.com/in/nicholasyue/</a><br>
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