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Re: [Condor-users] Condor and GPUs



On Thu, Jul 03, 2008 at 10:09:12AM -0400, Fr?d?ric Bastien wrote:
> >> If condor_status return the same value as the one seen while doing the
> >> negotiation, this will not work correctly as all slot don't see the
> >> same version. If I wait 5 minutes the value are correct.
> >
> > Yes, it takes another negotiation cycle for the master to notice. If
> > more jobs are matched before this cycle ends, your changed rules won't
> > be followed.
> 
> I'm not sure to understand well. When the master make match, did it
> have the good value? If yes, we could use it event if condor_status
> don't show the good value. I think condor can match some jobs between
> negotiation cycle; when a job finish it match one right away. But I
> don't know if it use the good information at that time. Do some one
> know?

As I understand it (and slightly different outputs from condor_q and condor_status
queries I'm using to monitor the state of the pool seem to support this):
the matcher can only use the information it has about individual slots.
Everything that happens between the actualisations of the machine (rather:
slot) classAds would be thin ice. AFAIK Condor makes a multi-stage transition
to make sure that a matched slot will actually be able to run the application
but AFAICT this doesn't involve a re-evaluation of the classAds.

In plain English: if the negotiator believes (from the previous update)
that a certain slot holds a set of resources, it will continue to believe
this (and act accordingly, matching jobs against that slot) until the classAds
are updated, which can take some minutes.

> What happen is that I see two step in the implementation of a good
> handgling of SMP machine: 1) allow to used them correctly, 2) (as you
> tell) optimize their usage. I thinks that when step 1 will be done, we
> would be able to use the current method for making rules for step 2.
> At least initially we could use it with not too bad result.

Of course. OTOH, what's a racing car worth when there's no steering wheel?

Cheers,
 Steffen