During an operation, an application runtime occasionally becomes longer or shorter than previously measured runtime despite running under the same conditions (e.g., with the same load module and input parameters). We call this issue "runtime fluctuation".

The runtime fluctuations disturb efficient operations of the K computer. If runtime exceeds the maximum elapsed time given by a job script, the computational resources will be uselessly consumed due to the incomplete termination of the program. And if runtime is getting short, the job running order should be disordered and rearranged by the job scheduler.

Therefore, Operations and Computer Technologies Division (運用技術部門) continued to investigate these issues and resolve them. In this talk, I will show some cases of the runtime fluctuations and solutions.