1. 05 Apr, 2013 1 commit
  2. 04 Apr, 2013 1 commit
    • Stephen Trofinoff's avatar
      Cray - NPPCU support patch · a6d3074d
      Stephen Trofinoff authored
          I am sending the latest update of my NPPCU-support patch for Slurm 2.5.0.  As before, this patch is applied over my basic BASIL 1.3 support patch.  The reason for this latest version is that it came to my attention, that certain jobs that should have been rejected by Slurm were allowed through.  I then further noticed that this would cause the backfill algorithm to slow down dramatically (often not being able to process any other jobs).
           The cause of the problem was that when I introduced the functionality into Slurm to properly set the "nppcu" (number of processors per compute unit) attribute in the XML reservation request to ALPS, I didn't also adjust the tests earlier in the code that eliminate nodes from consideration that do not have sufficient resources.  In other words, jobs that would exceed the absolute total number of processors on the node would be rejected as always (this is good).  Jobs that required the reduced number of "visible" processors on the node or less were allocated and worked fine (this is good).  Unfortunately, jobs that needed a number of processors somewhere in between these limits (let's call them the soft and hard limits) were allowed through by Slurm.  Making matters worse, when Slurm would subsequently try to request the ALPS reservation, ALPS would correctly reject it but Slurm would keep trying--this would then kill the backfilling.  In my opinion, these jobs should have been rejected from the onset by Slurm as they are asking for more processors per node than can be supplied.  If the user wants this number of processors they should specify the "--ntasks-per-core=..." (in our case "2" as that is the full number of hardware threads per core).  Obviously, this problem only appeared when I used CR_ONE_TASK_PER_CORE in the slurm.conf as I had modified the code to set nppcu to 1 when Slurm was configured with that option and the user didn't explicitly specify a different value.
          The patch appears to be working well for us now and so I am submitting it to you for your review.
      a6d3074d
  3. 02 Apr, 2013 2 commits
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  5. 30 Mar, 2013 1 commit
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  9. 26 Mar, 2013 5 commits