* Philip Kovacs <pkde...@yahoo.com> [190917 07:43]: > >> I suspect the question, which I also have, is more like: > >> > >> "What difference does it make whether I use 'srun' or 'mpirun' within > >> a batch file started with 'sbatch'." > > One big thing would be that using srun gives you resource tracking > and accountingof the individual job or step that you would not > otherwise get with mpirun.
Hello, thank you very much for all the feedback. From your responses I gathered that there is a broad consensus to use srun because of its tighter integration with Slurm. I have now also realized that srun and mpirun do indeed make a big difference in terms of accounting. For testing I've run two identical jobs today, both of them with #SBATCH --nodes=4 #SBATCH --tasks-per-node=16 #SBATCH --mem=8gb but the first batch script launched the application with srun, i.e. module load mpi/impi export I_MPI_PMI_LIBRARY=/opt/pmix/2.2.3/lib/libpmi.so srun ./stress whereas the second job script used mpirun to spawn the processes, i.e. module load mpi/impi mpirun ./stress Every process (rank) ran for 10 minutes, resulting in an overall CPU time of 10h and 40 minutes (= 4 nodes * 16 cores * 10 minutes). I have then compared all the accounting records of both jobs (as reported by `sacct´ command) and there are some noticeable differences in various fields for job step id 0. For the mpirun test case some of the fields appear really odd, e.g. AllocCPUS=4, NCPUS=4 and NTasks=4. I would have expected AllocCPUS=64, NCPUS=64 and NTasks=64 and that is exactly what `sacct´ reports for the srun test case. Also CPUTime=00:40:04 (reported for mpirun case) is weird compared to CPUTime=10:41:04 (reported for the srun case). Interestingly TotalCPU and UserCPU fields do match for both test cases. There are quite some more differences that I still need to understand. But in general, the accounting records for the srun test case seem to be more in line with my expectations. Thanks again. Best regards Jürgen -- Jürgen Salk Scientific Software & Compute Services (SSCS) Kommunikations- und Informationszentrum (kiz) Universität Ulm Telefon: +49 (0)731 50-22478 Telefax: +49 (0)731 50-22471
