[GE users] user feels penalized by share tree

Shannon V. Davidson svdavidson at swbell.net
Wed Jun 2 18:13:28 BST 2004


Sebastian / Andy,

You could charge less during non-peak periods by adjusting the execution 
host's cpu usage scaling factor:

    % qconf -mattr exechost usage_scaling cpu=0.1 <exec-host-name>


or you could implement a simple brokerage system with a monitoring 
script which sets the cpu usage scaling factor for a host based on how 
many jobs are waiting to run on that host:

    #!/bin/sh
    set +u
    host=$1
    if [ "$host" = "" ]; then
       echo usage: `basename $0` hostname
       exit 1
    fi
    while [ 1 = 1 ]; do
       jobs=`qstat -s p -l h=$host | egrep -v "^job-ID|^-----" | wc -l`
       if [ $jobs -eq 0 ]; then
          cpu_scale=0
       else
          cpu_scale=`echo "scale=2; 1.0 - (1.0 / ($jobs+1))" | bc`
       fi
       echo $jobs jobs are queued for $host, Setting CPU scaling factor
    to $cpu_scale
       qconf -mattr exechost usage_scaling cpu=$cpu_scale $host
       sleep 60
    done


Cheers,
Shannon


Andy Schwierskott wrote:

>Sebastian,
>
>  
>
>>One of my users was complaining about being penalized by the share tree policy
>>if he's using the cluster when otherwise it would be idle. Let us assume the
>>following situation:
>>
>>There are 20 nodes, 15 of which are free (have no job running) at night. The
>>user thinks it would be a good time to submit his jobs (which is not wrong).
>>
>>Say he submits 12 jobs which run all the night.
>>
>>On the next day, when other users are submitting jobs, he will have bad karma
>>(=less tickets) and feel 'penalized' for using the idle time of the cluster.
>>
>>I couldn't find a way to argue against that nor could I find a way to
>>'fix' that behaviour in SGE.
>>    
>>
>
>This behavior can't be "fixed" in a clean way today - the fix would be to
>introduce a brokerarge system where the "price" of resources depends on the
>demand for them.
>
>There are many good arguments why the implementation as it is today can be
>seen as fair - see the analogy to an empty hotel: you usually pay the same
>rate regardless of the number of guests. The user requested resources which
>were granted - from a global perspective it's certainly fair to argue that
>you have to pay for it.
>
>  
>
>>I'm running SGEEE 5.3p5 with a quite simple share tree and evenly distributed
>>tickets. Does someone have an idea how I could make the system 'feel a bit
>>more fair'?
>>    
>>
>
>If you are in the opinion that the behavior treats your users unfair, you
>may reduce the halflife time of the sharetree. Setting it to a few hours
>would decay past usage much faster.
>
>You also might consider to reset the sharetree usage every morning if a mid-
>or longterm fairs share is not an objective at your site. Or you may set the
>sharetree to e.g. 24 hours during day time and to a very short time (a few
>hours) during night time.
>
>Andy
>
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