[GE users] load sensor scaling or how to make a node picked last

craffi dag at sonsorol.org
Thu Feb 5 15:10:46 GMT 2009

Hi Russ,

Search the docs at http://wikis.sun.com/display/GridEngine/Home or the  
mailing list for "seqno" - SGE by default sorts all suitable queue  
instances by load and picks the "least busy" machine from among the  
suitable list.

You can override/influence this behavior by switching to seqno-based  
sorting where you can rank your machines with an integer number that  
is used in the sort.

If you tag all your new machines with a seqno of "0" and your older  
machines with a "1" then you'll find that the SGE scheduler will  
preferentially bias itself towards then newer machines.

Another option is to play games with adjustments to reported load  
averages. SGE will artificially spike the reported load average on a  
node right after a job lands there so that the scheduler does not slam  
an idle node with too much work all at once. By tweaking these numbers  
and the length of the delay time you can make your older machines  
appear to be busier than they really are. I've played games with that  
in the past to avoid certain machines over time.

Anyway, sequence based sorting is what you should look into first.


On Feb 5, 2009, at 10:02 AM, russray wrote:

> I have a SGE6.1 install and it is working well.  We have five linux  
> machines with all dual or quad cores except for our first machine  
> which is an older machine.  The install was purely default with no  
> changes other than setting up queues for the different type of jobs  
> to run.  No priorities for  users or projects exist.
> I would like to "handicap" the older machine so that it isn't picked  
> if no jobs are running.  qstat -f shows the load_avg of this machine  
> to be 0.00 when no job is running and therefore it is often picked  
> over other machines with more memory and cpu speed that have  
> load_avg of 0.01 or 0.02.  I would like to force a handicap onto the  
> slow machine so that it is basically picked almost last.  In other  
> words, if a job is running on a quad, I would rather have a second  
> job start on it than on the slow machine.
> How would I set this?  I've been looking through the manual and  
> can't seem to find what I need.
> Thanks,
> Russ


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