Re: [Condor-users] Need to have Condor not overload SMP machine

[Matt Hope <matthew.hope@xxxxxxxxx>]

On 10/12/05, Finch, Ralph <rfinch@xxxxxxxxxxxx> wrote:
> Background:  A LAN of 15 dual-cpu Windows XP machines, which because
> we've turned on mult-threading in some of the BIOS, some (but not all)
> appear as 4-cpu virtual machines.  When submitting a queue of 5, 4 jobs
> get sent to one desktop machine, because Condor thinks each VM is
> independent.  What we need is just one job per desktop machine
> regardless of the number of VMs so the desktop machine doesn't get
> overloaded.
>
> It seems I could accomplish this by setting
>
> NUM_CPUS = 1
>
> in the condor_config file, but "it's use is not recommended."  So how
> can I accomplish only 1 job per desktop machine?  If this is in the
> archives a point to the date is fine...

Have a separate config for your desktop machines which sets

NUM_VIRTUAL_MACHINES = 1

This is somewhat inefficient in the case where the machines spend a
considerable time totally idle since when nothing else is running ever
physical CPU could be doing something useful.

Note that if you jobs themselves make reasonable use of an SMP machine
this is not a problem and having 1 VM is fine (they still have access
to all the CPUS in the system)

Note that condor provides considerable resources for allowing desktop
machines to dynamically allocate resources so that a user on the
machine is likely to be relatively unaware of a jobs presence (by
suspending its jobs and if need be killing them)

Note that if the jobs are almost entirely CPU bound then simply
running all jobs with a renice increment would likely mean that you
could leave the jobs running whether the machine was in use or not.
This is tricky to guarantee unless you have tight control over what
programs will run in your pool...

Matt