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<p>Dear Quantum Espresso Experts,</p>
<p>I've been running a phonon calculation using QE-7.2 on both CPU and GPU and have noticed significantly different runtimes in the preparation step. I'd appreciate insights on how to improve the GPU performance.<br>
<b><br>
</b></p>
<p><b>CPU Setup:</b><br>
Nodes: 8<br>
Cores per Node: 128<br>
Parallelization: 8 images, 4 npools (calculation has 4 k-points)<br>
<br>
<b>GPU Setup:</b><br>
Nodes: 8<br>
GPUs per Node: 4<br>
OMP_NUM_THREADS: 1<br>
Parallelization: 8 images, 4 npools (calculation has 4 k-points)<br>
<br>
<br>
<br>
The preparation step, including steps like "Compute atoms," "Ewald sum," and charge density calculations, took around 9 hours on the CPU setup but over 24 hours on the GPU setup. Below is a section from the CPU calculation output before computing scf of each
representation mode:<br>
<br>
----------------------------------------------------------------</p>
<p> Compute atoms: 1, 2, 3, 4, 5, 6, 7, 8,<br>
9, 10, 11, 12, 13, 14, 15, 16,<br>
17, 18, 19, 20, 21, 22, 23, 24,<br>
<br>
<br>
<br>
Alpha used in Ewald sum = 2.8000<br>
<br>
negative rho (up, down): 9.781E-01 0.000E+00<br>
PHONON : 8h51m CPU 8h56m WALL<br>
<br>
<br>
<br>
Representation # 1 mode # 1<br>
<br>
Self-consistent Calculation<br>
-----------------------------------------------------------------------</p>
<p><br>
</p>
<p>Why might the preparation step for the GPU-based calculation be taking significantly longer? Are there specific optimizations or configurations I can apply to improve GPU performance in QE phonon calculations? </p>
<p>Thank you in advance for your help!<br>
</p>
<p><br>
</p>
<p>Best regards,</p>
<p>PhD student in Forschungszentrum Jülich<br>
Yin-Ying Ting<br>
</p>
<p>-- <br>
</p>
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<p>Forschungszentrum Jülich GmbH<br>
Institute of Energy and Climate Research<br>
Theory and Computation of Energy Materials (IEK-13)<br>
E-mail: <a href="mailto:y.ting@fz-juelich.de" class="moz-txt-link-freetext">y.ting@fz-juelich.de</a>
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Forschungszentrum Jülich GmbH<br>
52425 Jülich<br>
Sitz der Gesellschaft: Jülich<br>
Eingetragen im Handelsregister des Amtsgerichts Düren Nr. HR B 3498<br>
Vorsitzender des Aufsichtsrats: MinDir Stefan Müller<br>
Geschäftsführung: Prof. Dr. Astrid Lambrecht (Vorsitzende),<br>
Karsten Beneke (stellv. Vorsitzender), Dr. Ir. Pieter Jansens<br>
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