HPC cluster is available 24/7, and since simultaneous use of the cluster by several users is possible, virtual job queues have been introduced, which means that a job is put in a queue in case the amount of resources needed for it exceeds the amount of available HPC cluster resources (processor cores or memory). The queue time depends on the number of waiting jobs and the amount of resources claimed by the user.
To balance the HPC cluster load, HPC Centre holds the right to change the amount of HPC cluster resources (like processor cores) available to a single user or the number of simultaneous jobs.
Evaluate the performance of MPI jobs by using various number of nodes / cores to select the one most suitable for your job. Not always larger number of cores ensure faster execution of a job.
Do indicate the necessary walltime so that other users can forecast their queue time.
If the job entails intensive disk operation (I/O), it is advised to use a local SSD disc instead of the network directory (/home/*). The local disc is mounted to the directory /scratch/. When the job is completed, the files created in this directory should be removed manually.
If possible, avoid execution of jobs locally on the login node (ui-1.hpc.rtu.lv). Use it only to submit a job to a queue, to compile programs and test short jobs.
Users must avoid activities that might interfere with the work of other users (queue bypassing, exceeding the reserved amount of resources, etc.).