Re: [HTCondor-users] about START and RANK (and GPUs)

[John M Knoeller <johnkn@xxxxxxxxxxx>]

You are correct in thinking that Machine RANK only needs to rank jobs that the machine matches.

Machine RANK is all about preemption,  it will NOT prevent the machine from being matched to low-rank jobs even when a highly ranked job is already in the queue. If a user with a high priority has a job that matches but that the machine gives a low rank to  that job will still get the machine until it is preempted by a job that the machine ranks more highly. 

Job RANK, and Negotiator pre and post job RANK are combined into a sort key in the negotiator that is used to rank all of the potential matches before one is chosen.

-tj

-----Original Message-----
From: HTCondor-users [mailto:htcondor-users-bounces@xxxxxxxxxxx] On Behalf Of Michael Pelletier
Sent: Thursday, November 3, 2016 6:52 AM
To: HTCondor-Users Mail List <htcondor-users@xxxxxxxxxxx>
Subject: 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?

	-Michael Pelletier.

-----Original Message-----
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

Hi Jiang,

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 ...

best regards
        ~christoph


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