[gridengine users] cpu usage calculation

William Hay w.hay at ucl.ac.uk
Fri Aug 31 14:55:34 UTC 2018


On Fri, Aug 31, 2018 at 10:27:39AM +0000, Marshall2, John (SSC/SPC) wrote:
>    Hi,
>    When gridengine calculates cpu usage (based on wallclock) it uses:
>    cpu usage = wallclock * nslots
>    This does not account for the number of cpus that may be used for
>    each slot, which is problematic.
>    I have written up an article at:
>    https://expl.info/display/MISC/Slot+Multiplier+for+Calculating+CPU+Usage+in+Gridengine
>    which explains the issue and provides a patch (against sge-8.1.9)
>    so that:
>    cpu usage = wallclock * nslots * ncpus_per_slot
>    This makes the usage information much more useful/accurate
>    when using the fair share.
>    Have others encountered this issue? Feedback is welcome.
>    Thanks,
>    John

Used to do something similar (our magic variable was thr short for
threads).  The one thing that moved us away from that was in 8.x grid
engine binds cores to slots via -binding.

Rather than adding support for another mechanism to specify cores (slots,
-binding) it might be a better idea to support calculating cores per
slot based on -binding.

That said I'm not a huge fan of -binding.  If a job has exclusive access
to a node then the job can handle its own core binding.  If the job
doesn't have exclusive access then binding strategies other than linear
don't seem likely to be successful.

William
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