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Re: [HTCondor-users] about START and RANK (and GPUs)
This brings to mind a puzzle I'm in the middle of.
At what point do the job rank and the negotiator pre- and post-job rank expressions come into play?
I'm trying to get my GPU machines to prefer GPU jobs, but I seem to have something backwards - non-GPU jobs are going to the GPU machines first. Should I use machine rank or the pre/post-job rank configuration here? My current attempt is using negotiator_post_job_rank.
As was pointed out, the machine rank also implicates job preemption - Todd's "California marriage" quip from HTCondor Week this year - so I'd need to insure that is correctly configured.
Do I need to do both sides of the coin? Have non-GPU machines prefer non-GPU jobs as well as GPU machines preferring GPU jobs?
But then I remember that GPU jobs won't match non-GPU machines, so the "jobs-with-GPU" rank doesn't need to address non-GPU jobs, right? That would focus on which GPU has the most free memory or lowest die temperature or what have you... So I should apply rank for GPUs in such a way that it only comes into play when everything else about the job matches, i.e., no GPU required?
From: HTCondor-users [mailto:htcondor-users-bounces@xxxxxxxxxxx] On Behalf Of Beyer, Christoph
Sent: Thursday, November 03, 2016 1:45 AM
To: HTCondor-Users Mail List <htcondor-users@xxxxxxxxxxx>
Subject: Re: [HTCondor-users] about START and RANK
That's a sequential thing, the startd chooses a job that he prefers the most according to your rank expression.
Than before starting the job the startd evaluates the start expression to have a look if everything is ok to start the job.
For ex you could use the rank expression to prefer a multicore job and the start expression to only run it if the free disk space at start time is >200gb ...