[GE users] contemporary of -l slots=#

Reuti reuti at staff.uni-marburg.de
Wed Mar 30 21:30:13 BST 2005


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Quoting "Raphael Y. Rubin" <rafi at cs.caltech.edu>:

> I guess I'm a little unclear as to what the "logic behind" is, I
> wouldn't mind a short explanation.

To me means "one slot = one job (task) to run".
 
> So are you saying the PE warning basically assumes the user intended to
> use a PE and simply forgot?  And creating a PE to specify the number of

Yes, requesting more slots is for parallel jobs. If I got you correctly, you 
want to run a serial job, but exclusive on one machine with no other job on it.

> slots to reserve is bad, at least if there's no other driving purpose?

I said: personal taste - it's not bad per se, but I wouldn't like it. You will 
request a PE for a serial job.

> 
> I'm not so sure "virtual_free" is a safe alternative.  It seems to vary
> too wildly, even on unloaded systems.

When you set it for each exec host (qconf -me <host>), it will be exactly this 
value. And if you request exactly this value you get it.

> 
> Furthermore it doesn't seem to garuntee grid exclusivity (for the host),
> which is what
> our users occassionally need.

What do you mean grid exclusivity? One job in the whole cluster?

CU - Reuti

> 
> 
> I guess this gets back to the question of intent?  Is the slots thing
> specifically discouraged because there is an assumption that users
> shouldn't have the right to monopolize a machine?  Or is there something
> else going on?
> 
> Rafi
> 
> On Wed, Mar 30, 2005 at 09:53:37PM +0200, Reuti wrote:
> > Hi Raphael,
> > 
> > it's personal taste, but I wouldn't use any of the two options you offered
> - 
> > both are not refelecting the logic behind. Although: what I suggest is
> similar 
> > to the second:
> > 
> > - make the complex "virtual_free" consumable and requestable - default
> 1GB
> >                                                        (or what you like)
> > 
> > - attach this to each node with a value of the built in memory
> >                                     (complex_values   virtual_free=3.5GB)
> > 
> > - request 3.5GB in your qsub command -> single job on the node
> > 
> > 
> > With 4GB built in only 3.5GB are usable I think. Yes, it's nearly the same
> as 
> > your vslots, but this can also be used for a real request of just 2GB for
> 
> > larger jobs.
> > 
> > Cheers - Reuti
> > 
> > PS: IMO it's good to disallow the request for slots, to remind users to
> request 
> > a PE - maybe they forgot it by accident.
> > 
> > 
> > Quoting "Raphael Y. Rubin" <rafi at cs.caltech.edu>:
> > 
> > > I would like to configure my grid so that mortal users can grab
> exclusive
> > > access to a machine, using the normal submittion commands with little
> extra
> > > work.
> > > 
> > > Occassionally, a user wants to run a job exclusively for benchmarking,
> > > whether that's to test a class of machine or a specific job.
> > > 
> > > Also some jobs we know will be resource hogs, and we'd like to annotate
> them
> > > to indicate they are the equivalent of two or more normal jobs.
> > > 
> > > And of course there are various other nees that arrise, but the above two
> are
> > > the most common and important.  In the past we just use to specify "-l
> > > slots=n".  But as of sge5.3 that was discouraged.
> > > 
> > > 	error: denied: use parallel environments instead of requesting slots
> > > explicitly
> > > 	
> > > 		- from sge6
> > > 
> > > In sge 5.3, I had created a slots pe, after we first noticed the messages
> 
> > > about -l slots.  Here is an updated version of that pe (in a form for sge
> 
> > > 6).
> > > 
> > > pe_name           slots
> > > slots             999
> > > user_lists        NONE
> > > xuser_lists       NONE
> > > start_proc_args   /bin/true
> > > stop_proc_args    /bin/true
> > > allocation_rule   $pe_slots
> > > control_slaves    FALSE
> > > job_is_first_task TRUE
> > > urgency_slots     min
> > > 
> > > Alternatively, one can use a consumable complex, as described  in:
> > > 
> >
> 
http://gridengine.sunsource.net/servlets/BrowseList?list=users&by=thread&from=2
> > 530
> > > 
> > > or more simply:
> > > #name               shortcut   type        relop requestable consumable
> 
> > > default  urgency
> > > 
> >
> 
#------------------------------------------------------------------------------
> > ----------
> > > vslots              vs         INT         <=    YES         YES       
> 1
> > > 1000
> > > 
> > > Which is of course just the normal complex slots copied to a different 
> > > name to get around the explicit "-l slots" block.  Somehow this seems 
> > > wrong, a reincarnation of a technique deliberately killed for some reason
> 
> > > unknown to me.
> > > 
> > > 
> > > 
> > > Which style is prefered and why?
> > > What are the ramifications?
> > > Are there any behavioral differences?
> > > 
> > > 
> > > As for the prefered option, any suggestions to improve the above
> > > configurations?
> > > Also what's the best way to deploy, either globally, or to a set of
> queues?
> > > 
> > > 
> > > I know with sge 5.3, I was able to use:
> > > queue_list        all
> > > To deploy to my whole cell.
> > > 
> > > 
> > > 
> > > Also on a not complete tangent.  Does anyone have advice, or has anyone
> 
> > > written guidelines to optimize configuration of queues?  We are mostly 
> > > using dual cpu xeons with hyperthreading and 4G of ram.
> > > 
> > > Our jobs are mostly java, c, and lisp, single threaded (except the jvm 
> > > which forks its own stuff).  Jobs mostly run in a few hundred MB or less,
> 
> > > with a occasional memory hog which will eat a gig or two.
> > > 
> > > 
> > > Rafi Rubin
> > > California Institute of Technology
> > > 
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> > 
> > 
> > 
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