<html>Thank you for the information. Yes, at the beginning of the pw.x output it says:<br /> Parallel version (MPI), running on 64 processors<br /> R & G space division: proc/nbgrp/npool/nimage = 64<br /><br />Is bands.x parallelized at all? If so, where can I find information on that? There's nothing mentioned in the documentation:<br />http://www.quantum-espresso.org/wp-content/uploads/Doc/pp_user_guide.pdf<br />http://www.quantum-espresso.org/wp-content/uploads/Doc/INPUT_BANDS.html<br /><br />What could be the reason for bands.x taking many hours to calculate the bands? The foregoing pw.x calculation has already determined the energy for each k-point along a path (Gamma -> K -> M -> Gamma). There are 61 k-points and 129 bands. So what is bands.x actaully doing beside reformating that data? The input file job.bands looks like this:<br /> &bands<br /> prefix = 'st1'<br /> outdir = './tmp'<br />/<br />The calculation is initiated by<br />mpirun -np 64 bands.x < job.bands<br /><br />Maxim Skripnik<br />Department of Physics<br />University of Konstanz<br /><br />Am Samstag, 05. Dezember 2015 02:37 CET, stefano de gironcoli <degironc@sissa.it> schrieb:<br /> <blockquote type="cite" cite="56623FC2.9070705@sissa.it"> </blockquote><meta content="text/html; charset=windows-1252"
http-equiv="Content-Type"><div class="moz-cite-prefix">On 04/12/2015 22:53, Maxim Skripnik wrote:</div><blockquote cite="mid:bbc1c3d2d4083244.56620b59@limbe.rz.uni-konstanz.de" type="cite">Hello,<br /><br />I'm a bit confused by the parallelization scheme of QE. First of all, I run calculations on a cluster with usually 1 to 8 nodes, each of which has 16 cores. There is a very good scaling of pw.x e.g. for structural relaxation jobs. I do not specify any particular parallelization scheme as mentioned in the documentation, i.e. I start the calculations with<br />mpirun -np 128 pw.x < job.pw<br />on 8 nodes, 16 cores each. According to the documentation ni=1, nk=1 and nt=1. So in which respect are the calculations parallelized by default? Why do the calculations scale so well without specifying ni, nk, nt, nd?</blockquote>R and G parallelization is performed.<br />wavefunctions' planewaves, density planewaves and slices of real space objects are distributed across 128 processors. A report of how this is done is given at the beginning of the output.<br />Did you had a look to it ?<br /> <blockquote cite="mid:bbc1c3d2d4083244.56620b59@limbe.rz.uni-konstanz.de" type="cite">Second question is, whether one can speed up bands.x calculations. Up to now I start these this way:<br />mpirun -np 64 bands.x < job.bands<br />on 4 nodes, 16 cores each. Does it make sense to define nb for bands.x? If yes, what would be reasonable values?</blockquote> expect no gain. band parallelization is not implemented in bands.<br /><br />stefano<br /><br /><br /><br /><br /><br /><br /> <blockquote cite="mid:bbc1c3d2d4083244.56620b59@limbe.rz.uni-konstanz.de" type="cite">The systems of interest consist of typically ~50 atoms with periodic boundaries.<br /><br />Maxim Skripnik<br />Department of Physics<br />University of Konstanz<fieldset class="mimeAttachmentHeader"> </fieldset> <pre wrap="">_______________________________________________
Pw_forum mailing list
<a class="moz-txt-link-abbreviated" href="mailto:Pw_forum@pwscf.org">Pw_forum@pwscf.org</a>
<a class="moz-txt-link-freetext" href="http://pwscf.org/mailman/listinfo/pw_forum">http://pwscf.org/mailman/listinfo/pw_forum</a></pre></blockquote><br /><br /><br /> </html>