[Darshan-users] darshan-job-summary.pl reports non-stop IO

Kevin Harms harms at alcf.anl.gov
Tue May 7 17:26:49 CDT 2013

> Does anyone have any insight on why the job summary seems to depict continuous IO operations? Could the fact that the files are held open even though no IO to disk is actually happening be the reason the graphs suggest continuous IO operations?

  Yes, the graph shows the the first to last access time. So if you open a file, write to it, close it and do lots of stuff then re-open, update and close it again, you will see a continuous line. This graph "works" for checkpoint type files, where they are opened and used once, so you will see a clean split between the IO phases. Log type files that are modified periodically during the run will look like what you have.


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