Dear Gerhard, Thank you very much for your respond. I am a bit slow in catching up with what you are saying, may I rephrase what you've suggested and see is I could understand what you are suggesting:
For 4 k-points and 4 mkl thread - do you mean I would set 4 lines of "1:localhost" in the .machines file and set OMP_NUM_THREADS=4? And for the 2 k points and 2 mkl threads - do I set only 2 lines of "1:localhost" in the .machines file and set OMP_NUM_THREADS=2? If I am understanding you correctly, I will try both scenario and see which one is more efficient. Thank you so much for your time and help! Qiwen ------Original Message------ From:"Gerhard Fecher"<fecher at uni-mainz.de> To:"A Mailing list for WIEN2k users"<wien at zeus.theochem.tuwien.ac.at> Cc: Subject:Re: [Wien] OMP_NUM_THREADS Date:07/27/2011 03:17:21 PM(+0000) >If you have four "real" cores you may run in parallel either 4 k-points or 4 >mkl threads or 2 k points and 2 mkl threads > >In some cases it might be good to "switch off the virtual cores" in the bios, >at least with older processors/compilers this was faster, >but I did not check anymore. > >Ciao >Gerhard > >==================================== >Dr. Gerhard H. Fecher >Institut of Inorganic and Analytical Chemistry >Johannes Gutenberg - University >55099 Mainz >________________________________________ >Von: wien-bounces at zeus.theochem.tuwien.ac.at [wien-bounces at >zeus.theochem.tuwien.ac.at]" im Auftrag von "Dr Qiwen YAO >[Yao.Qiwen at nims.go.jp] >Gesendet: Mittwoch, 27. Juli 2011 14:13 >Bis: A Mailing list for WIEN2k users >Betreff: [Wien] OMP_NUM_THREADS > >Dear Wien2k users, > >We were told in the WIEN workshop that for mkl+multi-core cases, it might be >better having a setting of $OMP_NUM_THREADS =2. > >I have two questions in my mind: > >Q1. Does this apply to a 2 core system with 4GB RAM that is not running >parallel calculation (not K-point parallel nor mpi-parallel )? > > >Q2. Or this only apply to eg a quad core machine that runs on k-point parallel >or mpi-parallel calculation? > >I have a 4-Core Dell T7500 PC with 12GB RAM, each core is of two threads, so >in Susie/Linux or even in Windows, it all displays as a 8 CPU machine (so it >is in actuality a four-core CPU but each core is with 2 threads, so all the OS >sees it as a 8-core CPU). The actual info for this CPU is here if you like to >see the details of it: http://ark.intel.com/products/37111 > >I am setting up this machine running k-parallel calculation (not mpi-parallel >as I have got only one of this machine for the moment), I am pondering: > >Which of the following 2 scenarios is a better choice for a 90 atom supercell >calculation? > >Scenario 1. >.machines files is this: >------- >granularity:1 >1:localhost >1:localhost >1:localhost >1:localhost >1:localhost >1:localhost >1:localhost >1:localhost >extrafine:1 >---------- >and the OMP_NUM_THREADS=1 as default in my .bashrc file. >so no multi-threading but all k-parallelism. (With this setting, I do notice >after running the job for while - more than an hour say, the 8 CPUs shown in >the System Monitor says only two CPUs were really utilized at a time (and it >keep switching CPUs for the full-loading status, but mostly only two fully >loaded at a time) and the rest of the 6 CPUs weren't really doing much - some >of a few percentage of the load and others even on 0% - so I was wondering >maybe this setting isn't optimized? > >Scenario 2. >.machines files would be like this: >------- >granularity:1 >1:localhost >1:localhost >1:localhost >1:localhost >extrafine:1 >---------- >and set the OMP_NUM_THREADS=2 in my .bashrc file - I have not tried this >setting as I am not sure if this would be a workable setting? > >Or, both settings would work and won't make much difference in calculation >time length for a supercell calculation of 90 atoms? I am new to WIEN so I >could not fully understand the THREAD'ings in WIEN's aspect. > >On addition, for the above two .machines file setting, would it make any >difference if I put the real hostname in the place of "localhost"? > >Any comment would be greatly appreciated. > >Thank you! > >Kind regards, >Qiwen > >********************************************************** > >Dr QiWen YAO > >JSPS Fellow >Multifunctional Materials Group >Optical and Electronic Materials Unit >Environment and Energy Materials Research Division > >National Institute for Materials Science > >1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan >Phone: +81-29-851-3354, ext. no. 6482, Fax: +81-29-859-2501 > >********************************************************** > >_______________________________________________ >Wien mailing list >Wien at zeus.theochem.tuwien.ac.at >http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien >_______________________________________________ >Wien mailing list >Wien at zeus.theochem.tuwien.ac.at >http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien ********************************************************** Dr QiWen YAO JSPS Fellow Multifunctional Materials Group Optical and Electronic Materials Unit Environment and Energy Materials Research Division National Institute for Materials Science 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan Phone: +81-29-851-3354, ext. no. 6482, Fax: +81-29-859-2501 **********************************************************
