Thanks Giovanni for your suggestion. I will send the scaling tests a sson as possible.
Regards Pascal Le 06/02/2013 10:24, Giovanni Pizzi a ?crit : > Dear Pascal, > since you have more than one k-point, you could try to have each pool > within one node, so that only inter-pool communication occurs over > infiniband; for instance if you have 4 k-points you may try to use 4 > pools on 4 nodes (or possibly 2 pools on 2 nodes, or 4 pools on 2 > nodes, etc). > This kind of parallelization should scale pretty well, if your system > allows it (i.e. you have enough kpoints and your system fits in RAM). > Then, you can try to optimize the parallelization using the other > parallelization options. > > If you manage to do some scaling tests using the pools, could you > please report your results on this mailing list? > > Thanks, and best regards, > > Giovanni Pizzi > > > On 02/05/2013 10:12 PM, pascal boulet wrote: >> Dear all, >> >> I have a basic question about parallelism and scaling factor. >> >> First, I am running calculations on a cubic system with 58 atoms >> (alat=19.5652 a.u.), 540 electrons (324 KS states) and few k-points >> (4x4x4 grid=4 k-points), on 32 cores (4 nodes) but I can submit on many >> more. >> >> I guess the best thing to do is to parallelize the calculation on the >> bands but maybe also on the FFTs. We have an infiniband interconnection >> network between the nodes. >> >> What would you suggest as values for image/pools/ntg/bands ? >> >> I have made a SCF test calculation on 16 and 32 cores. For the SCF cycle >> (13 steps) I get the following timing: >> For 16 cores: total cpu time spent up to now is 22362.4 secs >> For 32 cores: total cpu time spent up to now is 17932.6 secs >> >> The speedup is "only" 25%. I would have expected a better speedup for >> such a small number of cores. Am i wrong? What is your experience? >> >> (For additional information, if helpful: QE 5.0.1 has been compiled with >> openMPI, intel 12.1 and FFTW 3.2.2.) >> >> thank you for your answers. >> >> Regards >> Pascal >> >> >> >> _______________________________________________ >> Pw_forum mailing list >> Pw_forum at pwscf.org >> http://pwscf.org/mailman/listinfo/pw_forum > > > -- > Giovanni Pizzi > Post-doctoral Research Scientist > EPFL STI IMX THEOS > MXC 340 (B?timent MXC) > Station 12 > CH-1015 Lausanne (Switzerland) > Phone: +41 21 69 31124 > > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://pwscf.org/mailman/listinfo/pw_forum -------------- next part -------------- A non-text attachment was scrubbed... Name: pascal_boulet.vcf Type: text/x-vcard Size: 413 bytes Desc: not available Url : http://pwscf.org/pipermail/pw_forum/attachments/20130206/9c16fe3c/attachment.vcf
