Steve Code that runs as part of the Cactus executable is running too late for this. At that time, OpenMP has already been initialized.
There is the environment variable "CACTUS_NUM_THREADS" which is checked at run time, but only if it is set (for backward compatibility). Most people do not bother setting it, leaving this error undetected. There is a warning output, but these are generally ignored. -erik On Thu, Dec 8, 2022 at 3:48 PM Steven R. Brandt <[email protected]> wrote: > > We could probably add some startup code in which MPI broadcasts the > OMP_NUM_THREADS setting to all the other processes and either checks the > value of the environment variable or calls omp_set_num_threads() or some > such. > > --Steve > > On 12/8/2022 9:03 AM, Erik Schnetter wrote: > > Spandan > > > > The problem is likely that MPI does not automatically forward your > > OpenMP setting to the other nodes. You are setting the environment > > variable OMP_NUM_THREADS in the run script, and it is likely necessary > > to forward this environment variable to the other processes as well. > > Your MPI documentation will tell you how to do this. This is likely an > > additional option you need to pass when calling "mpirun". > > > > -erik > > > > On Thu, Dec 8, 2022 at 2:50 AM Spandan Sarma 19306 > > <[email protected]> wrote: > >> Hello, > >> > >> > >> This mail is in continuation to the ticket, “Issue with compiling ET on > >> cluster”, by Shamim. > >> > >> > >> So after Roland’s suggestion, we found that using the –prefix > >> <openmpi-directory> command along with hostfile worked successfully in > >> simulating a multiple node simulation in our HPC. > >> > >> > >> Now we find that the BNSM gallery simulation evolves for only 240 > >> iterations on 2 nodes (16+16 procs, 24 hr walltime), which is very slow > >> with respect to, simulation on 1 node (16 procs, 24 hr walltime) evolved > >> for 120988 iterations. The parallelization process goes well within 1 > >> node, we received iterations - 120988, 67756, 40008 for procs - 16, 8, 4 > >> (24 hr walltime) respectively. We are unable to understand what is causing > >> this issue when openmpi is given 2 nodes (16+16 procs). > >> > >> > >> In the output files we found the following, which may be an indication > >> towards the issue: > >> > >> IINFO (Carpet): MPI is enabled > >> > >> INFO (Carpet): Carpet is running on 32 processes > >> > >> INFO (Carpet): This is process 0 > >> > >> INFO (Carpet): OpenMP is enabled > >> > >> INFO (Carpet): This process contains 1 threads, this is thread 0 > >> > >> INFO (Carpet): There are 144 threads in total > >> > >> INFO (Carpet): There are 4.5 threads per process > >> > >> INFO (Carpet): This process runs on host n129, pid=20823 > >> > >> INFO (Carpet): This process runs on 1 core: 0 > >> > >> INFO (Carpet): Thread 0 runs on 1 core: 0 > >> > >> INFO (Carpet): This simulation is running in 3 dimensions > >> > >> INFO (Carpet): Boundary specification for map 0: > >> > >> nboundaryzones: [[3,3,3],[3,3,3]] > >> > >> is_internal : [[0,0,0],[0,0,0]] > >> > >> is_staggered : [[0,0,0],[0,0,0]] > >> > >> shiftout : [[1,0,1],[0,0,0]] > >> > >> WARNING level 1 from host n131 process 21 > >> > >> in thorn Carpet, file > >> /home2/mallick/ET9/Cactus/arrangements/Carpet/Carpet/src/SetupGH.cc:426: > >> > >> -> The number of threads for this process is larger its number of > >> cores. This may indicate a performance problem. > >> > >> > >> This is something that we couldn’t understand as we asked for only 32 > >> procs, with num-threads set to 1. The command that we used to submit our > >> job was: > >> > >> ./simfactory/bin/sim create-submit p32_mpin_npn --procs=32 --ppn=16 > >> --num-threads=1 --ppn-used=16 --num-smt=1 --parfile=par/nsnstohmns1.par > >> --walltime=24:10:00 > >> > >> > >> I have attached the out file, runscript, submitscript, optionlist, machine > >> file for reference. Thanks in advance for help. > >> > >> > >> Sincerely, > >> > >> -- > >> Spandan Sarma > >> BS-MS' 19 > >> Department of Physics (4th Year), > >> IISER Bhopal > >> _______________________________________________ > >> Users mailing list > >> [email protected] > >> http://lists.einsteintoolkit.org/mailman/listinfo/users > > > > > _______________________________________________ > Users mailing list > [email protected] > http://lists.einsteintoolkit.org/mailman/listinfo/users -- Erik Schnetter <[email protected]> http://www.perimeterinstitute.ca/personal/eschnetter/ _______________________________________________ Users mailing list [email protected] http://lists.einsteintoolkit.org/mailman/listinfo/users
